Let's Join O and P as shown in the image below



In \(\triangle\)POR
-> OP = OR = Radius
=> \(\triangle\)POR is an isosceles triangle.

\(\angle\)OSP = \(90^{\circ}\) [ As \(\angle\)PSQ= \(90^{\circ}\) ]
And we know that, in an Isosceles Triangle the perpendicular drawn from the vertex tot he non equal side, bisects the side

=> OS will bisect PR
=> PS = SR

Now, consider \(\triangle\)PSQ and \(\triangle\)RSO
PS = SR (proved above)
OS = OQ (given)
And the included angle, \(\angle\)PSQ = \(\angle\)RSO = \(90^{\circ}\)
=> \(\triangle\)PSQ ≅ \(\triangle\)RSO [Congruent triangles, all corresponding sides and all corresponding angles will be equal]
=> PQ = OR
=> Quantity A = Quantity B

So, answer will C
Hope it helps!

Watch the following video to Learn Basics of Circles