If $\ { H } _ { p } /H _ { b }$

If $\ { H } _ { p } /H _ { b }$ is approximately equal to 1, then $H _ { e }$ is approximately equal to:

A) $H _ { b }$
B) $\ H_ { p }$
C) $\frac { H _ { p } + H _ { b } } { 2 }$
D) $\frac { H _ { p } } { 2 }$