Elements $A$ and $B$ with their respective electronic configurations $3d^{10} 4s^1$ and $4d^{10} 5s^1$ in their outermost shell are

• A
  Both non-metals
• B
  Both coinage metals
• C
  $A$ is a non-metal and $B$ is coinage metal
• D
  $A$ is a coinage metal and $B$ is non-metal