Simplify the Expression $\sqrt { 100 } - \sqrt { 144 }$

Multiple Choice

Simplify the expression. Assume all variables represent positive real numbers.
- $\sqrt { 100 } - \sqrt { 144 }$

A) $- 2$
B) $- \sqrt { 2 }$
C) $- 1$
D) $- 2 \sqrt { 11 }$