Explanation

(d)
Aufbau principle does not give the correct arrangement of filling up of atomic orbitals in copper and chromium because half-filled and completely filled electronic configuration of Cr and Cu have lower energy and therefore, more stable.
$Cr(Z = 24):1s^{2},2s^{2}2p^{6},3s^{2}3p^{6}3d^{5},4s^{1}$
$Cu(Z = 29):1s^{2},2s^{2}2p^{6},3s^{2}3p^{6}3d^{10},4s^{1}$