The displacement of a body moving along a straight line is given by $x=\mathrm{pt}^{2}+\mathrm{qt}+\mathrm{r}$ where $\mathrm{p}, \mathrm{q}, \mathrm{r}$ are constants and $\mathrm{t}^{\prime}$ represents time. The acceleration of the body will
(a) remain a constant
(b) decrease
(c) increase
(d) first increase and then decrease