What is the angle between the lines whose direction cosines are proportional to $(2,3,4)$ and $(1,-2,1)$ respectively?

• Correct answer
  A

  $90^{\circ}$
• B

  $60^{\circ}$
• C

  $45^{\circ}$
• D

  $30^{\circ}$

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