Concept:The question tests logical sequencing of sentences to form a coherent paragraph. Each part follows a natural flow from general facts to specific details and then to a contrasting problem.
Explanation:Start with part R: oceans regulate global temperature and climate. This directly extends the opening statement about oceans covering Earth's surface.
Next is part S: they provide food and employment to millions. This adds human benefits, logically following the climate role.
Then part P: marine species are crucial for food chains. This narrows down to the ecological importance, linking to the previous sentence.
Finally part Q: but plastic waste threatens marine life. This introduces a problem, creating a need for conservation mentioned in sentence 6.
Thus the correct order is R, S, P, Q.
Answer:Option A: RSPQ