Rationalize the Denominator and Simplify $\frac { 4 } { \sqrt { 10 } + 3 }$

Rationalize the denominator and simplify. Assume that all variables represent positive real numbers.
- $\frac { 4 } { \sqrt { 10 } + 3 }$

A) $4 \sqrt { 10 } - 12$
B) $4 \sqrt { 10 } - 3$
C) $\frac { 4 \sqrt { 10 } + 12 } { 20 }$
D) $4 \sqrt { 10 } + 12$