A particle moves along a straight line. Its velocity v(t) (in m/s) is described as follows: it increases linearly from 0 at t=0 to 6 at t=3 and then remains constant at 6 for 3<t≤5. Which statement best describes the particle's acceleration on 0<t≤5 s?
a) It is constant at 2 m/s2 for the entire interval.
b) It is 0 m/s2 for 0<t<3 and 2 m/s2 for 3<t≤5.
c) It is 2 m/s2 for 0<t<3 and 0 m/s2 for 3<t≤5.
d) It is −2 m/s2 for 0<t<3 and 0 m/s2 for 3<t≤5.