In order to convet but-2-enal to but-2-enoic acid which of the following reagent is required ?

In order to convet but-2-enal to but-2-enoic acid which of the followi

1.	In order to convet but-2-enal to but-2-enoic acid which of the following reagent is required ?
Answer» `Br_(2)` water `KMnO_(4)` Tollen's reagent `LiAlH_(4)` Solution :Tollen's reagent causes oxidation of `-CHO` to `-COOH` but it is UNABLE to bring about oxidation of `C = C` bond