Rationalize the Denominator and Simplify $\frac { 21 } { \sqrt { 21 } + 1 }$

Multiple Choice

Rationalize the denominator and simplify. $\frac { 21 } { \sqrt { 21 } + 1 }$

A) $\frac { 21 ( \sqrt { 21 } - 1 ) } { 20 }$
B) $\frac { 21 \sqrt { 21 } - 1 } { 20 }$
C) $\frac { 20 ( \sqrt { 21 } - 1 ) } { 21 }$
D) $\frac { \sqrt { 21 } - 21 } { 20 }$
E) $21 ( \sqrt { 21 } - 1 )$