Perform the Operation and Give the Answer as a Fraction $- \frac { 1 } { 3 } - \frac { 1 } { 18 }$

Multiple Choice

Perform the operation and give the answer as a fraction in lowest terms.
- $- \frac { 1 } { 3 } - \frac { 1 } { 18 }$

A) $- \frac { 1 } { 36 }$
B) $- \frac { 1 } { 8 }$
C) $- \frac { 7 } { 4 }$
D) $- \frac { 7 } { 18 }$