If p if and only if q, then p is described as:
ANecessary but never sufficient
BSufficient but never necessary
CNeither necessary nor sufficient
DNecessary and sufficient for q
Answer & Solution
Correct answer: D. Necessary and sufficient for q
1. The implication runs both ways.
2. q if and only if p says the same.
3. So p is necessary and sufficient for q.
_Source: NCERT Class 11 Mathematics, Chapter 14, Mathematical Reasoning._
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