Answer: Option A
:
A
This is a definition based question.
We defined as following :
$K_{\alpha }$ : When electronis transition takes place from L-shell to K-shell or vacancy shifts from K-shell to L-shell (this is what the energy level diagram indicates)
$K_{\beta }$ :When electronis transition takes place from M-shell to K-shell or vacancy shifts from K-shell to M-shell (this is what the energy level diagram indicates)
$K_{\gamma }$ :When electronis transition takes place from N-shell to K-shell or vacancy shifts from K-shell to N-shell (this is what the energy level diagram indicates)
Got the answer!!