Suppose $\vec{a}, \vec{b}$ and $\vec{c}$ be three vectors of length $1, \frac{1}{2}$ and 1 respectively such that
$\vec{a} \times(\vec{a} \times \vec{c})+\vec{b}=\overrightarrow{0}$
The acute angle between $\vec{a}$ and $\vec{c}$ is

• A

  $15^{\circ}$
• Correct answer
  B

  $30^{\circ}$
• C

  $45^{\circ}$
• D

  $60^{\circ}$

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