Find the Value of B That Gives the Function the Given

Multiple Choice

Find the value of b that gives the function the given maximum value.
- $f ( x ) = - x ^ { 2 } + b x + 2 ;$ maximum value 6

A) $b = - 2$ or $b = 2$
B) $b = - 4$ or $b = 4$
C) $b = 4$
D) $b = 2$