Fig. 105 shows a quick return mechanism. The crank \(O A\) rotates clockwise uniformly. \(O A=2 \mathrm{~cm}, O O^{\prime}=4 \mathrm{~cm}\). The ratio of time for forward motion to that for return motion is

(a) 0.5

(b) 2.0

(c) \(\sqrt{12}\)

(d) 1 .

Fig.105 B