Change the Radical to Simplest Radical Form $- \frac { 4 \sqrt { 20 } } { 6 \sqrt { 35 } }$

Multiple Choice

Change the radical to simplest radical form. $- \frac { 4 \sqrt { 20 } } { 6 \sqrt { 35 } }$

A) $\frac { 35 \sqrt { 20 } } { 6 }$
B) $- \frac { \sqrt { 35 } } { 21 }$
C) $4 \sqrt { 7 }$
D) $- \frac { 4 \sqrt { 7 } } { 21 }$