Electron configuration of d orbital

Chemistry Level 2

Which of the following elements is not consistent with its electron configuration at ground state?

\text{Co: [Ar]}3d^{7}4s^{2}

\text{Cr: [Ar]}3d^{5}4s^{1}

\text{Cu: [Ar]}3d^{9}4s^{2}

\text{Mn: [Ar]}3d^{5}4s^{2}