The radius of a circular plate increases at the rate of 0.25 cm/sec when heat is applied . If the radius of the plate is 7 cm., the area increase rate is -

A \( 10\ cm^2\sec^{-1} \)

B \( 11\ cm^2\sec^{-1} \)

C \( 0.5\ cm^{2\ }\sec^{-1} \)