Hydrogen peroxide acts both as an oxidising and as a reducing agent depending upon the nature of the reacting species. In which of the following cases H$$_2$$O$$_2$$ acts as a reducing agent in acid medium?

A

MnO$$_4^-$$

B

Cr$$_2$$O$$_7^{2-}$$

C

SO$$_3^{2-}$$

D

KI