\(A B C D\) is a four bar mechanism, in which \(A D\) is the fixed link, and link \(B C\), is in the form of a circular disc with centre \(P\). In which one of the following cases \(P\) will be the instantaneous centre of the disc?

(a) If it lies on the perpendicular bisector of line \(B C\)

(b) If it lies on the intersection of the perpendicular bisectors of \(B C\) and \(A D\)

(c) If it lies on the intersection of the perpendicular bisectors of \(A B\) and \(C D\)

(d) If it lies on the intersection of the extensions of \(A B\) and \(C D\).

B P + A O Fig.59 D