Find the Domain of the Function $$g ( p ) = \sqrt { 4 - p ^ { 2 } }$$

Multiple Choice

Find the domain of the function.
$$g ( p ) = \sqrt { 4 - p ^ { 2 } }$$

A) $- 2 \leq p \leq 2$
B) $p \leq - 2$ or $p \geq 2$
C) $p \geq 0$
D) $p \leq 2$
E) all real numbers