Assertion: `CH_(3)Br+AgCNrarrCH_(3)NC+AgBr`
Reason: `CN` is an ambident ion .
A. If both assertion and reason are true and the reasone is the correct explanation of the assertion .
B. If both assertion and reason are true but reason is not the correct explanation of the assertion .
C. If assertion is true but reasone is false
D. If assertion is false but reason is true .