If Vector $\vec { A }$ Has Components A_x = -3 $\overrightarrow { \mathbf { B } }$

Multiple Choice

If vector $\vec { A }$ has components A_x = -3.0 lb and A_y = -4.0 lb, and vector $\overrightarrow { \mathbf { B } }$ has components B_x = 3.0 lb and B_y = -8.0 lb, what is the magnitude of vector $\overrightarrow { \mathrm { C } }$ = $\vec { A }$ - $\overrightarrow { \mathbf { B } }$ ?

A) 13 lb
B) 16 lb
C) 140 lb
D) 7.2 lb