Alexander turned his attention towards India, since he had conquered Persia. Which one of the statements below is logically valid and can be inferred from the above sentence? A. Alexander would not have turned his attention towards India had he not conquered Persia. B. Alexander was not ready to rest on his laurels, and wanted to march to India. C. Alexander was not completely in control of his army and could command it to move towards India. D. Since Alexander's kingdom extended to Indian borders after the conquest of Persia, he was keen to move further.

GATE 2015 · General Aptitude · Verbal Reasoning · medium

Answer: A. Alexander would not have turned his attention towards India had he not conquered Persia.

1. Extract the causal structure: The sentence establishes: Conquering Persia (cause A) -> Turning attention to India (effect B). The word 'since' functions as 'because', creating a direct causal implication.
2. Apply contrapositive reasoning: Contrapositive of 'Conquered Persia -> Turned to India' is 'Had he NOT conquered Persia -> Would NOT have turned to India'. This exactly matches option A: 'Alexander would not have turned his attention towards India had he not conquered Persia.'
3. Reject options B, C, D: B introduces 'not resting on laurels' — not stated. C introduces 'not in control of army' — not stated. D introduces 'kingdom extended to Indian borders' — not stated. All three go beyond the given sentence and introduce unsupported assumptions.