A dipeptide, "x" on complete hydrolysis gives "y" and "z". "y" on treatment with aq. HNO$$_2$$ produces lactic acid. On the other hand "z" on heating gives a cyclic molecule.

Based on the information given, the dipeptide X is:

A

valine-glycine

B

alanine-glycine

C

valine-leucine

D

alanine-alanine