Provide an Appropriate Response $p$ Must Be Determined $\mathrm { p }$

Provide an appropriate response.
-To perform a hypothesis test of two population proportions, the pooled estimate or $p$ must be determined. The polled estimate, $\mathrm { p }$ , is

A) $\hat { p } = \frac { x _ { 1 } + x _ { 2 } } { n _ { 1 } + n _ { 2 } }$
B) $\hat { p } = \frac { x _ { 1 } } { n _ { 1 } } + \frac { x _ { 2 } } { n _ { 2 } }$
C) $\hat { p } = \frac { n _ { 2 } x _ { 1 } + n _ { 1 } x _ { 2 } } { n _ { 1 } + n _ { 2 } }$
D) $\hat { p } = \frac { x _ { 1 } + x _ { 2 } } { n _ { 1 } n _ { 2 } }$