Perform the Operations and Simplify the Result When Possible $\frac { a + b } { 2 } + \frac { a - b } { 7 }$

Multiple Choice

Perform the operations and simplify the result when possible. $\frac { a + b } { 2 } + \frac { a - b } { 7 }$

A) $\frac { 2 ( 9 a + 5 b ) } { 9 }$
B) $\frac { 5 a - 9 b } { 7 }$
C) $\frac { 9 a + 5 b } { 14 }$
D) $\frac { 9 a + 5 b } { 9 }$
E) $\frac { 9 a + b } { 7 }$