The Oscillation of the 2 $x = 3.0 \cos ( 4.0 t + 0.80 )$

Multiple Choice

The oscillation of the 2.0-kg mass on a spring is described by $x = 3.0 \cos ( 4.0 t + 0.80 )$ where x is in centimeters and t is in seconds.What is the force constant of the spring?

A) 4.0 N/m
B) 0.80 N/m
C) 16 N/m
D) 32 N/m
E) 2.0 $\pi$ N/m