Simplify Assume All Variables Represent Nonnegative Values $\frac { \sqrt { 24 a } } { \sqrt { 4 a } }$

Simplify. Assume all variables represent nonnegative values.
- $\frac { \sqrt { 24 a } } { \sqrt { 4 a } }$

A) $\sqrt { 6 }$
B) $6 \sqrt { a }$
C) 6
D) $\sqrt { 6 a }$