Answer
The correct answer is (c)
Work Step by Step
The electronc configuration of $Fe$ is $[Ar] 3d^6 4s^2$. So, $Fe^{2+}$ has two less electrons; hence its electronic configuration is $Fe$ is $[Ar]4s^0 3d^6 $
**Note, the electrons are taken out of the 4s sub shell before the 3d sub shell.
