Assertion : The electronic configuration of K) (19) is `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)4s^(1)`.
Reason : Energy of `4s lt 3d`. This is decided by Aufbau principle.
A. if both assertion and reason are correct and reason is correct explanation for assertion .
B. If both assertion and reason are correct but reason in not correct explanation for assertion.
C. If assertion is correct but reason is incorrect.
D. If both assertion and reason are incorrect.