An object of mass 0.2kg is hung from a spring whose spring constant is k=80Nm(-1). The body is subject to a resistive force given by -bv, where v is its velocity, and b=4kgs(-1). If the object moves upwards with a velocity of 2 m/s at t=0, its velocity after 2 seconds will be:

a) -4 m/s
b) -3.2 m/s
c) -2.4 m/s
d) -1.6 m/s