A ray of light travelling through rarer medium is incident at very small angle $i^{}$ on a glass slab and after refraction its velocity is reduced by $20\%.$ The angle of deviation is

• A

  $\frac{i}{8}$
• Correct answer
  B

  $\frac{i}{5}$
• C

  $\frac{i}{2}$
• D

  $\frac{4i}{5}$

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