Find the Domain of the Function $g ( p ) = \sqrt { 81 - p ^ { 2 } }$

Multiple Choice

Find the domain of the function. $g ( p ) = \sqrt { 81 - p ^ { 2 } }$

A) -9 ? p ?9
B) p ? -9 or p? 9
C) p ? 0
D) p ? 9
E) all real numbers