A Balloon in the Shape of a Sphere Is Deflating $t$

A balloon in the shape of a sphere is deflating. Given that $t$ represents the time, in minutes, since it began losing air, the radius of the balloon (in $\mathrm{cm}$ ) is $r(t) =20-\mathrm{t}$ . Let the equation $\mathrm{V}(\mathrm{r}) =\frac{4}{3} \pi \mathrm{r}^{3}$ represent the volume of a sphere of radius $r$ . Find and interpret $(\mathrm{V} \circ \mathrm{r}) (\mathrm{t})$ .

A) $(V \circ r) (t) =20-\frac{4}{3} \pi(20-t) ^{3}$ ; this is the volume of the air lost by the balloon (in $\mathrm{cm}^{3}$ ) as a function of time (in minutes) .
B) $(V \circ r) (t) =\frac{4}{3} \pi(20-t) ^{3}$ ; this is the volume of the air lost by the balloon (in $\left.\mathrm{cm}^{3}\right)$ as a function of time (in minutes) .
C) $(V \circ r) (t) =\frac{4}{3} \pi(20-t) ^{3}$ ; this is the volume of the balloon (in $\left.\mathrm{cm}^{3}\right)$ as a function of time (in minutes) .
D) $(\mathrm{V} \circ \mathrm{r}) (\mathrm{t}) =\frac{4}{3} \pi(\mathrm{t}-20) ^{3}$ ; this is the volume of the balloon (in $\mathrm{cm}^{3}$ ) as a function of time (in minutes) .