The correct answer is (c). Deimachus was a Greek historian who lived in the 4th century BC. He is best known for his work on the history of Alexander the Great, which is now lost. However, there is no evidence that he ever accompanied Alexander on his campaign to India.
Nearchus was a Greek admiral who served under Alexander the Great. He was responsible for leading the fleet that sailed back from India to Persia after Alexander’s death. Onesicritus was a Greek historian who also accompanied Alexander on his campaign to India. He wrote a book about the expedition, which is now lost. Aristobulus was a Greek engineer who also accompanied Alexander on his campaign to India. He wrote a book about the expedition, which is still extant.
It is possible that Deimachus did accompany Alexander on his campaign to India, but there is no evidence to support this claim. The other three men are known to have been with Alexander in India, and their accounts of the expedition are valuable sources of information about this period of history.