The correct option is D Cr
The electronic configuration of Mn is [Ar]4s23d5. So, it has 5 unpaired electrons.
The electronic configuration of Fe is [Ar]4s23d6. So, it has 4 unpaired electrons.
The electronic configuration of Tc is [Kr]5s24d5. So, it has 5 unpaired electrons.
The electronic configuration of Cr is [Ar]4s13d5. So, it has 6 unpaired electrons.