If A and B are two non-empty sets having $n$ elements in common, then what is the number of common elements in the sets $\mathrm{A} \times \mathrm{B}$ and $\mathrm{B} \times \mathrm{A}$ ?

• A

  $n$
• Correct answer
  B

  $n^2$
• C

  $2 n$
• D

  zero

Hence, the correct answer is option: 'B'.