What is the angle between two planes $2 x-y+z=4$ and $x+y+2 z=6$ ?

• A

  $\frac{\pi}{2}$
• Correct answer
  B

  $\frac{\pi}{3}$
• C

  $\frac{\pi}{4}$
• D

  $\frac{\pi}{6}$

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