Provide an Appropriate Response $f ( n ) = \sqrt { n ^ { 2 } + 4 } - \sqrt { n ^ { 2 } - 4 }$

Multiple Choice

Provide an appropriate response.
-Let $f ( n ) = \sqrt { n ^ { 2 } + 4 } - \sqrt { n ^ { 2 } - 4 }$ . What is $f ( n )$ approximately equal to as $n$ gets large? Hint: Compute various examples on your calculator.

A) $\frac { 4 } { n ^ { 2 } }$
B) $\frac { 4 } { \sqrt { n } }$
C) $\frac { 4 } { 2 n }$
D) $\frac { 4 } { n }$