Let $F$ be the focus of the parabola $C : y ^ { 2 } = 4 x$ , point $A$ is on $C$ , point $B ( 3,0 )$ , if $| A F | = | B F |$ , then $| A B | =$ A. 2 B. $2 \sqrt { 2 }$ C. 3 D. $3 \sqrt { 2 }$
Let $F$ be the focus of the parabola $C : y ^ { 2 } = 4 x$ , point $A$ is on $C$ , point $B ( 3,0 )$ , if $| A F | = | B F |$ , then $| A B | =$
A. 2
B. $2 \sqrt { 2 }$
C. 3
D. $3 \sqrt { 2 }$