Rewrite the Quadratic Function in Standard Form by Completing the Square

Multiple Choice

Rewrite the quadratic function in standard form by completing the square.
- $$f ( x ) = x ^ { 2 } + 3 x + 1$$

A) $f ( x ) = \left( x + \frac { 3 } { 2 } \right) ^ { 2 } + \frac { 5 } { 4 }$
B) $f ( x ) = ( x + 3 ) ^ { 3 } - 9$
C) $f ( x ) = ( x - 3 ) ^ { 3 } - 9$
D) $f ( x ) = \left( x + \frac { 3 } { 2 } \right) ^ { 2 } - \frac { 5 } { 4 }$