Which of the following is not correct for the electron distribution in the ground state for $4s$ and $3d$ orbitals?

• A
  $Co (Z=27): [Ar] 4s^2 3d^7$ (represented as $4s: \uparrow \downarrow, 3d: \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow, \uparrow$)
• B
  $Ni (Z=28): [Ar] 4s^2 3d^8$ (represented as $4s: \uparrow \downarrow, 3d: \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow, \uparrow$)
• C
  $Cu (Z=29): [Ar] 4s^2 3d^9$ (represented as $4s: \uparrow \downarrow, 3d: \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow$)
• D
  $Zn (Z=30): [Ar] 4s^2 3d^{10}$ (represented as $4s: \uparrow \downarrow, 3d: \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow, \uparrow \downarrow$)