A manufacturing company of bulbs has 3 units $\mathrm{A}, \mathrm{B}$ and C which produce $25 \%$, $35 \%$ and $40 \%$ of the bulbs respectively. Out of the bulbs produced by A, B, C units, $5 \%, 4 \%$ and $2 \%$ are defective respectively. If a bulb is chosen at random and found to be defective, then the probability that it is produced by unit B is

• Correct answer
  A

  $\frac{28}{69}$
• B

  $\frac{28}{71}$
• C

  $\frac{29}{67}$
• D

  $\frac{25}{69}$

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