A point starts moving in a straight line with a certain acceleration. At a time t after beginning of motion the acceleration suddenly becomes retardation of the same value. The time in which the point returns to the initial point is

(1) $\sqrt{2t}$

(2) $\left(2+\sqrt{2}\right)\text{\hspace{0.17em}}t$

(3) $\frac{t}{\sqrt{2}}$

(4) Cannot be predicted unless acceleration is given