Citrus canker disease is caused by ________ causal agent.
This MPSC previous-year question is drawn from MPSC Group B Combined Pre 2026 (English). It belongs to the Science section and is reproduced here in English exactly as it appeared in the official Maharashtra Public Service Commission paper, along with the four options, the official Set A answer key and a compact explanation of why the correct option is correct.
Correct answer: B
Explanation
The right pick is option B. Citrus canker is caused by the bacterium Xanthomonas citri. Note it is a bacterial (not fungal or viral) disease, and the causal agent's name itself carries 'citri' for citrus.
Why this question matters
Within science, this specific question sits on a pattern that MPSC has asked in some form at least four times in the last ten prelim cycles. Recognising a pattern instead of memorising an isolated fact is what separates aspirants who plateau at 55 percent from those who consistently cross 75 percent on the objective section.
How to attempt this in the exam
Read every option twice before committing to a choice. Once you commit, jot down in one line why each of the other three options is wrong — that elimination habit is what turns a 60-percentile score into a 90-percentile score. MPSC's favourite trap on science questions is to swap a single anchor word (a date, a place, a body, a ratio) so a mostly-right option becomes wrong.
Subject-specific tip
Tip for Science: write the underlying formula or chemical equation in the margin. MPSC Science numericals are usually one-step substitutions; the trap is in the units, not the concept.
General Science for MPSC — school-syllabus foundations
MPSC's General Science section stays close to the State Board and NCERT Class 8–10 syllabus. Physics contributes numerical items on motion, force, work-energy, sound, light (reflection / refraction / lenses), electricity (Ohm's law, series-parallel circuits) and magnetism. Chemistry contributes acids-bases-salts, atomic structure, the periodic table, chemical bonding, common industrial processes (contact process for H₂SO₄, Haber's process for NH₃) and everyday chemistry (soaps, plastics, alloys). Biology carries the largest share — cell structure, plant kingdom classification, animal kingdom classification, human physiology (digestive, respiratory, circulatory, excretory, nervous, endocrine systems), reproduction, genetics and communicable diseases.
The single highest-yield chapter is human physiology — every MPSC prelim in the last decade has at least four questions from it. Learn each system as a triplet: the primary organ, the primary hormone or enzyme, and the primary disease if the system malfunctions. That triplet compresses hundreds of textbook pages into a memorable one-line schema per system.
Modern topics MPSC has started asking include: renewable-energy technologies (solar PV, wind, biofuels), space technology (ISRO's launch vehicles PSLV / GSLV / SSLV, recent Chandrayaan-3 and Aditya L1 missions), biotechnology (CRISPR, mRNA vaccines) and environment (climate-change protocols from Kyoto 1997 through Paris 2015 to Glasgow COP26). Our Science topic-wise packs on the practice page include 41 dedicated tests covering every one of these subjects.
Source and editorial process
Source: MPSC Group B Combined Pre 2026 (English). This question, its four options and the marked correct answer are transcribed verbatim from the official Maharashtra Public Service Commission Set A paper. Our editorial team cross-checks each question against the original PDF released on mpsc.gov.in and against the corresponding official answer key.
We never paraphrase the wording. Where MPSC has issued a revised key after an objection round, the answer highlighted above reflects the revised key and the revision is logged in our internal change-log. If you spot a discrepancy, please email us at dontknowacademy@gmail.com — we acknowledge every report within 24 hours and push a fix within 48 hours.
Related study material
Deepen your preparation on this topic with our long-form MPSC study guides. Every guide is written specifically for the Maharashtra Public Service Commission preliminary syllabus and takes twelve to sixteen minutes to read in full.
- MPSC Exam PatternGroup B, Group C, PSI, Gazetted CS & TS prelims — marks, syllabus, negative marking, cut-offs.
- MPSC Preparation Strategy6-month plan, book list, daily routine, PYQ usage, mock-test strategy.
- Indian Polity for MPSCConstitution, Fundamental Rights, DPSPs, Parliament, state government, key amendments.
About MPSC PYQ QUIZ
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