Write an Equation to Describe the Variation $\mathrm { p }$

Write an equation to describe the variation. Use k for the constant of proportionality.
- $\mathrm { p }$ varies jointly as the square of $\mathrm { q }$ and the square of $\mathrm { r }$ .

A) $\mathrm { p } = \mathrm { kq } ^ { 2 } \mathrm { r } ^ { 2 }$
B) $p q ^ { 2 } r ^ { 2 } = k$
C) $p + q ^ { 2 } + r ^ { 2 } = k$
D) $p = k + q ^ { 2 } + r ^ { 2 }$