Explanation:

1, 2 and 3

 The eminent Buddhist writers Nagarjuna, Asvaghosha, Parsva & Vasumitra flourished at the court of Kanishka. Charaka, the most celebrated authority on Ayurveda was the court physician of Kanishka & Mathara, a politician of rare merit, was his minister. Nagarjuna was the great exponent of Mahayana doctrine & Asvaghosha, a multifaceted personality, was known as a poet, musician, scholar & zealous Buddhist monk. Vasumitra presided over the 4th Buddhist Council.