Read the following statements and answer the four items that follow.
Five cities P, Q, R, S, and T are connected by different modes of transport as follows:
P and Q are connected by boat as well as rail.
S and R are connected by bus and boat
Q and T are connected by air only
P and R are connected by boat only
T and R are connected by rail and bus.
Which mode of transport would help one to reach R starting from Q, but without changing the mode of transport?