Assertion : Insertion of recombinant DNA within the coding sequence of 阝-galactosidase results in colourless colonies.
Reason : Presence of insert results in inactivation of enzyme 阝-galactosidase known as insertional inactivation.

A. Assertion is true but reason is false.
B. Both assertion and reason are false.
C. Both assertion and reason are true and the reason is the correct explanation of the assertion.
D. Both assertion and reason are true and the reason is not the correct explanation of the assertion.