Diphenylamine reagent gives a deep blue colour with a solution. It contains

Options

A. `Sn^(2+)`
B. `NO_(2)^(-)`
C. `NO_(3)^(-)`
D. `Fe^(3+)`

Explanation

`NO_(2)^(-),NO_(3)^(-)` and `Fe^(3+)` being oxidising agents oxidise diphenylamine giving deep blue colour.