A. The oldest fossil grasses are just 70 million years old, although grass may have evolved a bit earlier than that. B. There have been land plants for 465 million years, yet there were no flowers for over two-thirds of that time. C. The equally-familiar grasses appeared even more recently. D. Flowering plants only appeared in the middle of the dinosaur era.
Sentences B and D talk of flowers and flowering plants. Sentence B talks of how land plants existed without flowers for several millions of years. Sentence D talks of when flowering plants appeared. It is clear D follows B. Sentence C speaks of “equally familiar grasses?. So obviously, some other example- in this case, flowering plants- precedes this. Sentences A and C talk of the evolution of grasses. A follows C. The question is " Arrange the sentences in the correct order " The order is BDCA Hence, the answer is BDCA Choice D is the correct answer.