A Patient with High Blood Pressure Who Weighs 168 Pounds $10 \frac { 1 } { 8 }$

A patient with high blood pressure who weighs 168 pounds is put on a diet to lose 21 pounds in three months. The patient loses $10 \frac { 1 } { 8 }$ pounds the first month and $9 \frac { 5 } { 8 }$ pounds the second month. How much weight must be lost the third month for the goal to be achieved?

A) $2 \frac { 1 } { 4 }$ pounds
B) $1 \frac { 1 } { 4 }$ pounds
C) $2 \frac { 1 } { 2 }$ pounds
D) $1 \frac { 1 } { 2 }$ pounds
E) $3 \frac { 1 } { 2 }$ pounds