Question

P: Biographies of great men can also help us in learning good manners. Q: Courtesy and politeness is the key to good manners. R: No doubt these are little words but if they are spoken at the right moment and in a soft and sweet voice, they are bound to work wonders. S: The use of polite words like "Sorry", "Please", "Thank you", "Beg your pardon", "Sir" etc. creates a healthy impact on the minds of others.

Q: Answer-P: Biographies of great men can also help us in learning good manners. Q: Courtesy and politeness is...

Here, Q is the introductory sentence. We can understand that R follows S because S talks about some words and R talks about these words. P can be placed right after Q and it will form a coherent paragraph. So, the correct order of the sentences is QPSR.