Let an acute-angled triangle $A B C$ be inscribed in a circle whose centre is the origin. Let $B=(3,4)$ and $C=(-4,3)$. Then $\angle B A C$ is

• A

  $\pi / 5$
• Correct answer
  B

  $\pi / 4$
• C

  $\pi / 3$
• D

  $\pi / 2$

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