Find a Polar Equation of the Conic with Focus at the Pole

Multiple Choice

Find a polar equation of the conic with focus at the pole that has the eccentricity and equation of directrix. $e = 1$ , $r \cos \theta = 7$

A) $r = \frac { 7 } { 1 + 2 \cos \theta }$
B) $r = \frac { 3 } { 1 + \sin \theta }$
C) $r = \frac { 7 } { 1 - \cos \theta }$
D) $r = \frac { 7 } { 1 + \cos \theta }$
E) $r = \frac { 3 } { 1 - \cos \theta }$