A Pebble Is Dropped into a Calm Pond, Causing Ripples $r ( t ) = 0.2 t$

A pebble is dropped into a calm pond, causing ripples in the form of concentric circles.The radius (in feet) of the outer ripple is $r ( t ) = 0.2 t$ , where t is the time in seconds after the pebble strikes the water.The area of the circle is given by the function $A ( r ) = \pi r ^ { 2 }$ .Find and interpret $( A \circ r ) ( t )$ .

A) $( A \circ r ) ( t ) = 0.2 \pi t$ ; $( A \circ r ) ( t )$ represents the area of the circle at time t.
B) $( A \circ r ) ( t ) = 0.2 \pi t ^ { 2 }$ ; $( A \circ r ) ( t )$ represents the area of the circle at time t.
C) $( A \circ r ) ( t ) = 0.04 \pi t$ ; $( A \circ r ) ( t )$ represents the area of the circle at time t.
D) $( A \circ r ) ( t ) = 0.04 \pi t ^ { 2 }$ ; $( A \circ r ) ( t )$ represents the area of the circle at time t.
E) $( A \circ r ) ( t ) = 0.04 \pi t ^ { 3 }$ ; $( A \circ r ) ( t )$ represents the area of the circle at time t.