The correct options are
C Varahamihira - Surya Siddhanta
D Aryabhatta - Brihat Samhita
Charaka was a great physician who wrote Charaka-Samhita. Brahmagupta speculated about the law of gravitation. Brahmashutika Siddhanta is one of his notable works. The Surya Siddhanta written by Aryabhatta deals with astronomy. Varahamihira is also another notable mathematician and astronomer. His work Brihat Samhita deals with mathematics, botany, physical geography, and astronomy. He discovered the motions of the moon. He stated that the moon revolves around the earth and that the two together revolve around the sun.