A sphere and cube made of same material and having same surface area are heated to the same temperature and kept in the same surroundings. The ratio of their initial rates of
cooling will be:

• A

  $\sqrt{\frac{\mathrm{\pi }}{6}}:1$

• B

  $\sqrt{\frac{\mathrm{\pi }}{2}}:1$

• C

  $\sqrt{\frac{\mathrm{\pi }}{3}}:1$

• D

  $\frac{\mathrm{\pi }}{\sqrt{3}}:1$