In the Fig. 28 shown crank \(A B\) is \(15 \mathrm{~cm}\) long and is rotating at \(10 \mathrm{rad} / \mathrm{s} . C\) is vertically above \(A\). \(C A\) equals \(24 \mathrm{~cm} . C\) is swivel trunnion through which \(B D(40 \mathrm{~cm})\) slides. If \(A B C D\) becomes a vertical line during its motion, the angular velocity of the swivel trunnion at that instant will be

(a) zero

(b) \((100 / 25) \mathrm{rad} / \mathrm{s}\)

(c) \((100 / 15) \mathrm{rad} / \mathrm{s}\)

(d) \((100 / 10) \mathrm{rad} / \mathrm{s}\).

BO Fig.28 A