Let p and q be distinct prime numbers such that
$$\begin{aligned}
& a = p ^ { 4 } \cdot q ^ { 2 } \\
& b = p ^ { 2 } \cdot q ^ { 3 }
\end{aligned}$$
Which of the following is the greatest common divisor of numbers a and b?\\
A) $p ^ { 5 } \cdot q ^ { 4 }$\\
B) $p ^ { 4 } \cdot q ^ { 3 }$\\
C) $p ^ { 3 } \cdot q ^ { 4 }$\\
D) $p ^ { 2 } \cdot q ^ { 2 }$\\
E) $p ^ { 2 } \cdot q ^ { 3 }$