In this section each item consists of six sentences of a passage. The first and sixth sentences are given in the beginning as S1 and S6. The middle four sentences in each have been jumbled up and labelled P, Q, R and S. You are required to find the proper sequence of the four sentences
S1: The houses in the Indus Valley were built of baked bricks.
S6: They led outside into covered sewers which ran down the side of the streets.
P: This staircase sometimes continued upwards on to the roof.
Q: ·Access to the upstairs rooms was by a narrow stone staircase at the back of the house.
R: The drains were built in the walls.
S: The houses had bathrooms and water closets, rubbish chutes and excellent drainage systems.
The proper sequence should be.

Options

A. SP QR
B. PS QR
C. Q RPS
D. SQPR