An Object Moves Along a Line in Such a Way $s ( t ) = t ^ { 3 } - 9 t ^ { 2 } + 15 t + 2$

Multiple Choice

An object moves along a line in such a way that its position at time t is $s ( t ) = t ^ { 3 } - 9 t ^ { 2 } + 15 t + 2$ .Find the velocity and acceleration of the object at time t.When is the object stationary?

A) $v ( t ) = 3 t ^ { 2 } - 18 t + 15$ ; a(t) = 6t - 18; t = 3
B) $v ( t ) = 3 t ^ { 2 } - 6 t + 15$ ; a(t) = 6t - 6; t = 1
C) $v ( t ) = 3 t ^ { 2 } - 18 t + 15$ ; a(t) = 6t - 18; t = 1
D) $v ( t ) = 3 t ^ { 2 } - 18 t + 15$ ; a(t) = 6t - 18; t = 1 and 5