An information processing system consists of seven stations - M,N,P,Q,R,S and T. Every request is classified as either normal or priority. Requests for information are processed in the following ways:
(i) All normal requests are received by either M or N, and all priority requests are received by M or Q.
(ii) All requests processed by M are then sent to T.
(iii) All requests processed by N are then sent to S.
(iv) Normal requests processed by T'are then sent to P, priority requests processed by T are then sent to Q.
(v) All requests processed by S are then sent to cither T or P.
(vi) Normal requests processed by P are then sent to Q, and prioriy requests processed by P are then sent to R.
(vii) All requests processed by Q are then sent to either P or R.
(viii) R is the station which issues a final response.
Any of the following can be true EXCEPT .

Options

A. M sends a request to T.
B. S sends a request to T.
C. S sends a request to P.
D. S sends a request to Q.

Answer

D

Explanation

This is a "network" set. Begin by drawing the diagram :
All normal requests are received by either M or N, and all priority requests are received by M or Q :

All requests processed by Q are then sent to either P or R:

The diagram shows that S cannot send a request to Q, though he can send one to P, who in turn can send one to Q.