Sodium extract is heated with concentrated `HNO_(3)` before testing for halogens because :
A. Ag reacts faster with halides in acidic medium.
B. Silver halides are totally insoluble in nitric acid.
C. `Ag_(2)S` and AgCN are soluble in acidic medium.
D. `S(2-) " and" CN^(-)`, if present, are decomposed by conc. `HNO_(3)` and hence do not interfere in the test.
