A block of mass 3 kg, initially at rest, is pulled along a friction less, horizontal surface with a force shown as a function of time t by the graph. The acceleration of the block at t = 2 s is
(A) 3/4 m/s2
(B) 4/3 m/s2
(C) 2 m/s2
(D) 8 m/s2
(E) 12 m/s2