Who is the youngest in the group? In a group of four people: I. Amit is older…

Concept: In a data-sufficiency ordering question, a statement (or a set of statements) is sufficient only if it uniquely fixes the answer to the specific question asked — here, who is youngest — even if it leaves some other relative positions undetermined. Two partial orderings chain together transitively when one statement places a shared entity at its lower end and the other statement places that SAME entity at its upper end — that complementary placement is what links the relations into one broader order; merely sharing an entity without such complementary placement does not by itself combine two orderings.

1. Statement I alone gives Tanuja > Amit > Mahesh (older to younger). It says nothing about Rahim, so Rahim could sit above Tanuja, between any two of them, or below Mahesh — more than one ranking remains possible, so Statement I alone is insufficient.

2. Statement II alone gives Mahesh > Rahim. It says nothing about how Amit or Tanuja compare with Rahim, so Rahim could still be older than Amit or Tanuja — more than one ranking remains possible, so Statement II alone is insufficient.

3. Combine the two statements using the entity they share, Mahesh: Statement I places Mahesh at its lower end (Amit > Mahesh), and Statement II places that same Mahesh at its upper end (Mahesh > Rahim). Because Mahesh is the lower bound of one and the upper bound of the other, the two relations link transitively into one complete order for all four people: Tanuja > Amit > Mahesh > Rahim.

4. In this complete order, Rahim occupies the last position — Rahim is the youngest.

Cross-check: Could any other person be the youngest instead? Statement II fixes Rahim strictly below Mahesh, and Statement I fixes Mahesh strictly below both Amit and Tanuja, so Rahim is below all three of the others in every ordering consistent with both statements — no alternative ranking survives, confirming the order is unique.

Result: Both statements together are needed to fix the complete order and identify the youngest person; neither statement alone does so. This matches: Both the Statements, 1 and 2 are necessary.