Assertion: The order of reactivity of alkyl halides towards `S_(N^1)` reaction in tertiary halidegtsecondary halidegtprimary halide.
Reason: The reaction follows carbocation mechanism.
A. If both assertion and reason are true and reason Is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assetion is true but reason is false.
D. If both assertion and reason are false.