Correct Answer - D
`Co^(3 +) rarr [Ar] 3 d^(6) 4 s^(0)`, number of uparied electrons = 4
`Fe^(2 +) rarr [Ar] 3 d^(6) 4 s^(0)`, number of uparied electrons = 4
`Co^(2 +) rarr [Ar] 3 d^(7) 4 s^(0)`, number of uparied electrons = 3
`Fe^(3 +) rarr [Ar] 3 d^(6) 4 s^(0)`, number of uparied electrons = 5