In the following items, each passage consists of six sentences. The first and sixth sentence are given in the beginning as `S_(1)` and `S_(6)`. The middle four sentences in each have been jumbled up. These are labelled P, Q, R ans S. You are requested to find out the proper sequence of the four sentences and mark according on the Answer Sheet.
`S_(1):` Why do birds migrate in spite of the heavy loss of life on the way?
`S_(6):` The migration of birds thus is a fascinating study, indeed.
P: But birds also migrate during winter.
Q: Primarily they migrate during the summer.
R: Also they cannot endure the summer heat.
S: And the main reason now is not hunger but availability of the nesting sites.
The proper sequence should be

Options

A. Q P S R
B. P Q R S
C. R S P Q
D. Q R P S