Answer:
The correct answer is option d. "India was a separate continent until 45 million years ago".
Step-by-step explanation:
135 million years ago, Pangea was a single continent that became separated into Laurasia in the north and Gondwana in the south. India was part of Gondwana along with Australia, South America, Antarctica and Africa. However, as a result of tectonic activity India got separated from Gondwana. This period of time at which India was a separated continent is the factor that most likely explains why animals and plants in India differ greatly from species in nearby southeast Asia. At being a separated continent, India's plants and animals go through an independent evolutionary process which made them very different an unique from nearby species.