Assertion: Addition of `Br_(2)` to `1`-butane gives two optical isomers.
Reason: The product contains one asymmetric carbon atoms.
A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true and the reason is the correct explanations of the assertion
C. If the assertion is true but reason is false
D. If assertion is false but reason is true.