In the following question, select the odd letters from the given alternatives

Concept: In this type of classification question, each 3-letter group names keys on a standard QWERTY keyboard. In a valid group, every consecutive pair of letters sits on neighbouring (physically adjacent) keys, so the three letters form one connected chain across the keyboard. The odd group is the one where some pair of letters is NOT on neighbouring keys, so the chain breaks.

Applying this to each option, in the order given:

1. ASD: A and S are neighbouring keys in the home row; S and D are also neighbouring keys in the home row. Both pairs are adjacent, so the chain holds.

2. WSX: W and S are neighbouring keys in the same staggered key-column used for touch-typing (top row to home row); S and X are also neighbouring keys in that same column (home row to bottom row). Both pairs are adjacent, so the chain holds.

3. BVA: B and V are neighbouring keys in the bottom row, but V and A are several keys apart with no shared neighbour between them, so this pair is NOT adjacent, and the chain breaks here.

4. FCX: F and C are diagonally neighbouring keys; C and X are neighbouring keys in the bottom row. Both pairs are adjacent, so the chain holds.

Cross-check: ASD, WSX, and FCX each keep every consecutive pair on neighbouring keys, so all three form a valid, unbroken chain. Only BVA fails to form a complete chain, since V and A are not neighbouring keys. Hence BVA is the odd letters.