If $\vec{A} \times \vec{B}=\vec{B} \times \vec{A}$, then the angle between $A$ and $B$ is

• Correct answer
  A

  $\pi$
• B

  $\pi / 3$
• C

  $\pi / 2$
• D

  $\pi / 4$

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