Find out the correct sequence of sentences which are labelled as P, Q, R and S. The history of mankind is P. and steady progress Q. continuous change R. the history of S. from barbarism to refinement The correct sequence should be

Step-by-step solution

RQPS. The verb "is" in the opening part cannot be followed by the conjunction "and". This eliminates option (1) from consideration. Part (R), which ends with a preposition, cannot be placed at the end of the sentence. This eliminates option (3) from consideration. Neither does part (S) fit after the opening part nor does ( R ) fit after ( Q ) . This eliminates option (4) from consideration. The only remaining option (2) is used to complete the sentence and it is found to be grammatically correct.