Correct Answer - C
`S_(N)1` reation involves the formation of carbocations hence higher the stability of carbocation more will be the reactivity of the parent alkyl halide Thus tertiary carbocation formed from ( c ) is stabilized by two phenyl groups and one methyl group hence most stable
`C_(6)H_(5) - underset(C_(6)H_(5))underset(|)overset(CH_(3))overset(|)C-Br rarrC_(6)H_(5)-underset(CH_(3))underset(uarr)underset(|)overset(+)C-C_(6)H_(5)` .
