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CAT 2025Slot 3VARCQues & Sol

Verbal AbilityMedium

Question

The given sentence is missing in the paragraph below. Decide where it best fits among the options 1, 2, 3, or 4 indicated in the paragraph.

Sentence: In each of the affected males, the genetic defect was located to the X chromosome in the region of p11-12.

Paragraph: The first suggested evidence of a human genetic mutation associated with aggressive behaviour came from a study in 1993. _____(1)____. Genetic and metabolic studies were conducted on a large Dutch family in which several of the males has a syndrome of borderline mental retardation and abnormal behaviour. _____(2)____. The undesirable behaviour included impulsive aggression, arson and exhibitionism. _____(3)____. A point mutation was identified in the eighth exon of the monoamine oxidase A (MAOA) structural gene which changes glutamine to a termination codon. _____(4)____.

Options

Solution

1. Key Idea & Flow

The paragraph follows a tightly structured scientific narrative — moving from the introduction of a study, to identification of an affected group, to description of their behaviour, and finally to the genetic basis of that behaviour. The key progression is: 'The undesirable behaviour included impulsive aggression, arson and exhibitionism' at blank (3), followed by 'A point mutation was identified in the eighth exon of the monoamine oxidase A (MAOA) structural gene.' The missing sentence — which identifies the chromosomal location of the genetic defect — acts as a crucial bridge between the behavioural description and the specific molecular finding. In scientific writing, the convention is to move from broad genetic location (chromosome region) to a precise molecular mutation, and that is exactly the role this sentence plays.

2. Elimination Approach

🔴 Option D (Blank 1): This blank comes immediately after the opening line about the 1993 study. At this point, the paragraph has not yet introduced the Dutch family or the affected males. Placing a sentence that says 'In each of the affected males...' here creates a reference without an antecedent — the reader has no idea who 'the affected males' are. This is a classic pronoun-without-referent error, making this placement logically impossible.

🔴 Option C (Blank 2): Blank (2) appears right after the Dutch family and their syndrome are introduced, but before the specific behaviours are described. At this stage, the narrative is still in the 'who' phase — identifying the subjects. Introducing a chromosomal location here skips over the behavioural description entirely, disrupting the natural flow from subjects -> behaviour -> genetics.

🟡 Option B (Blank 4): This is the most tempting distractor. Blank (4) comes after the MAOA point mutation is identified, and one might argue that chromosomal location could serve as a concluding detail. However, this placement reverses the scientific logic — you cannot describe a specific exon-level mutation first and then zoom out to a general chromosomal region. That would be going from specific to general, which violates standard scientific reporting convention and feels like a redundant afterthought.

🟢 Option A (Blank 3): Blank (3) sits perfectly between the behavioural description ('impulsive aggression, arson and exhibitionism') and the specific MAOA mutation. The missing sentence shifts the narrative from 'what these males did' to 'where the genetic problem lies' — at the chromosomal level. The next sentence then zooms in further to the exact exon and point mutation. This general-to-specific genetic progression is both scientifically accurate and logically seamless.

3. Final Conclusion

Answer = Option A (Blank 3) ✅

Always map the missing sentence's function — here, it serves as a 'zoom-in bridge' from behaviour to broad genetics, before the paragraph narrows further to a specific molecular mutation, making Blank (3) the only structurally coherent placement.