The acceleration of a bus is given by a（t） =α*t, where α = 1.2 m/s^3. If the bus’s velocity at time t = 1.0s is 5.0 m/s, what is its velocity at time t = 2.0 s（）

A. 6.8 m/s

B. 5.6 m/s

C. 4.5 m/s

D. 7.6 m/s

E. 8 m/s

F. 5 m/s