Simplify the Radical Expression $- 8 \sqrt { 7 } - 6 \sqrt { 63 }$

Multiple Choice

Simplify the radical expression. Assume all variables represent positive real numbers.
- $- 8 \sqrt { 7 } - 6 \sqrt { 63 }$

A) $- 26 \sqrt { 7 }$
B) $- 14 \sqrt { 7 }$
C) $26 \sqrt { 7 }$
D) $- 10 \sqrt { 7 }$