The correct option is A Kanishka
Charak was one of the principal contributors to Ayurveda and is chiefly known for being the author of Charak Samhita. He is regarded as "Father of Indian Medicine". He lived during the reign of Kanishka, the king of the Kushan dynasty that ruled over the northern part of the Indian subcontinent, Afghanistan, and possibly areas of Central Asia north of the Kashmir region.