A 2kg block on a frictionless horizontal surface starts from rest at x=0. It is subjected to a force that is 8N from x=0 to x=1m and then varies with position as F(x)=4xN from x=1m to x=2m (with x in metres and the force along +x). The speed of the block after it has travelled 2m is closest to
a) 5.3ms−1
b) 3.7ms−1
c) 2.8ms−1
d) 4.5ms−1