The correct option is A 36
First inert gas which contains d-electrons is Kr.
Here in this,
Total number of d-electrons=10
Total number of p-electrons=6+6+6=18
Total number of s-electrons=2+2+2+2=8
Difference in total number of p- and s- electrons=18-8=10, which is equal to total number of d-electrons.
So, inert gas is Kr, atomic no. 36.