Question: What is Suman's rank from the top in a class of forty students ?…

Concept: in this data-sufficiency format, an option describing a group of statements (such as "any two of the three") is correct when at least two of the given pieces of information — not necessarily every possible pairing — are enough between them to pin down exactly one numeric value for what is asked; a pairing that only reproduces a bookkeeping identity true for any arrangement of the unknowns adds no new information and does not count.

1. Statement II alone fixes Deepak's position: in a class of 40, a rank of 23rd from the bottom converts to (40 − 23 + 1) = 18th from the top.

2. Combine I with II: Statement I places Suman 3 ranks below Deepak from the top, so Suman's rank from the top = 18 + 3 = 21st. That is one determinable value, so I and II together are sufficient.

3. Combine II with III: Statement III places Suman 3 ranks above Deepak from the bottom, so Suman's rank from the bottom = 23 − 3 = 20th, i.e. (40 − 20 + 1) = 21st from the top. That is also one determinable value, so II and III together are sufficient.

4. Combine I with III without II: Statement I gives Suman's rank from the top in terms of Deepak's rank from the top; Statement III gives Suman's rank from the bottom in terms of Deepak's rank from the bottom. Because rank-from-top + rank-from-bottom = 41 for every student in this class of 40, adding the two relations produces an identity that holds automatically for any actual position — it never isolates a single value by itself.

Cross-check: Statement II combined with either of the other two statements converges on the identical rank, 21st from the top, while I and III alone only reproduce the definitional identity — confirming II is the pivot clue that some second statement must join for a unique determination, though not that one particular second statement is mandatory.

Result: two different two-statement combinations — both built around Statement II — independently pin down the identical unique rank, so sufficiency does not require one single fixed pair or all three statements; it is satisfied by any two of the given pieces of information taken together, matching the recorded answer.