Question 4 A particle moves along the x-axis so that at time t2 0 its position is given by x(t) = 21 - 21 + 72t- 53. At what time tis the particle at rest? A t = 1 only B t = 3 only C t = 7/2 only D t = 3 and t = 7/2 E t = 3 and t = 4