Concept:The correct sequence of sentences forms a logical paragraph about energy sources and their future.
Explanation:The opening sentence (S1) introduces coal and oil as power sources.
The next sentence (Q) says these sources may not be exhausted very soon, which directly continues the idea.
Then (P) contradicts by stating they are not inexhaustible, creating a realistic turn.
After that, (R) suggests a time will come when other sources must be used, following logically from the limitation.
Finally, (S) lists alternative future sources like forests, water, wind, and withered vegetables, leading to the closing sentence (S6) about nuclear energy.
Thus the correct order is Q, P, R, S.
Answer:Option B: Q P R S