The electronic configuration of copper $({_{29}}Cu)$ is

• A
  $1s^2, 2s^2 2p^6, 3s^2 3p^6 3d^9, 4s^2$
• B
  $1s^2, 2s^2 2p^6, 3s^2 3p^6 3d^{10}, 4s^1$
• C
  $1s^2, 2s^2 2p^6, 3s^2 3p^6, 4s^2 4p^6$
• D
  $1s^2, 2s^2 2p^6, 3s^2 3p^6 3d^{10}$