"There is also evidence, from the fossil record, that, in the past, some living organisms became extinct and new ones emerged. The best model, so far, to explain such events is the theory of evolution."

Your first sentence seems to be talking about evolution but the secomd says "the theory of evolution". Could you clarify please?

Don't fall for this, Shim. There's no correct answer. He'll stalk you for ever more, I assure you!