Displacement (x) of a particle is related to time (t) as:
                      $\mathrm{x}=\mathrm{at}+{\mathrm{bt}}^2-{\mathrm{ct}}^3$
 where a, b and c are coonstants of the motion. The velocity of the particle when its acceleration is zero is given by

• A

  $\mathrm{a}+\frac{{\mathrm{b}}^2}{\mathrm{c}}$

• B

  $\mathrm{a}+\frac{{\mathrm{b}}^2}{2\mathrm{c}}$

• C

  $\mathrm{a}+\frac{{\mathrm{b}}^2}{3\mathrm{c}}$

• D

  $\mathrm{a}+\frac{{\mathrm{b}}^2}{4\mathrm{c}}$