The radius of a circle is increasing at the rate of $2 \text{ cm/sec}$. The rate at which its area is increasing when the radius of the circle is $5 \text{ decimeters}$ is:

• A
  $100 \pi \text{ cm}^2/\text{sec}$
• B
  $200 \pi \text{ cm}^2/\text{sec}$
• C
  $2000 \pi \text{ cm}^2/\text{sec}$
• D
  $20 \pi \text{ cm}^2/\text{sec}$