Omar AhmedIs this answer the only correct answer? I think 'c' is correct ,too. Yes. I think 'c' is even better because the sky being clear is an evidence that it won't rain. Yes. Am I right?
Those are both OK, but the question stem is not very idiomatic. In a statement of opinion (think, believe), we transfer any negation in the subordinate clause to the main clause.
I don't think it will rain. / I don't think it's going to rain.
CJ