A Stone Is Thrown into a Pond $( \mathrm { A } \cdot \mathrm { r } ) ( \mathrm { t } )$

Multiple Choice

A stone is thrown into a pond. A circular ripple is spreading over the pond in such a way that the radius is increasing at the rate of 2.6 feet per second. Find a function, r(t) , for the radius in terms of t. Find a function, A(r) , for the area of the ripple in terms of r . Find $( \mathrm { A } \cdot \mathrm { r } ) ( \mathrm { t } )$

A) $( A \circ r ) ( t ) = 2.6 \pi t ^ { 2 }$
B) $\left( A \rho ^ { \circ } \right) ( t ) = 6.76 \pi ^ { 2 } t$
C) $( \mathrm { A } \quad \circ \mathrm { r } ) ( \mathrm { t } ) = 5.2 \pi \mathrm { t } ^ { 2 }$
D) $\left( A { } ^ { \circ } r \right) ( t ) = 6.76 \pi t ^ { 2 }$