The correct option is (a) Uniform retardation
Easy explanation: We have, x = a + bt + ct^2 ……….(1)
Let, v and f be the velocity and acceleration of a particle at time t seconds.
Then, v = dx/dt = d(a + bt + ct^2)/dt = b + ct ……….(2)
And f = dv/dt = d(b + ct)/dt = c ……….(3)
Clearly, when c < 0,implies f < 0.
Hence in this case the particle moves withan uniform retardation.