A body cools from a temperature of $60^{\circ} \mathrm{C}$ to $50^{\circ} \mathrm{C}$ in 10 minutes and $50^{\circ} \mathrm{C}$ to $40^{\circ} \mathrm{C}$ in 15 minutes. The time taken in minutes for the body to cool from $40^{\circ} \mathrm{C}$ to $30^{\circ} \mathrm{C}$ is

• Correct answer
  A

  $30$
• B

  $20$
• C

  $25$
• D

  $40$

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