Assertion (A): Harshavardhana convened the Prayag Assembly. Reason (R): He wanted to popularise only the Mahayana form of Buddhism.

The correct option is A because both statements are true and the reason explains the assertion. Harshavardhana convened the Prayag Assembly, also known as the Maha Moksha Parishad, which he held every five years. While he was a tolerant ruler who respected various faiths, the primary objective of his major assemblies, including the one at Kannauj and the subsequent gathering at Prayag, was to highlight and popularize the doctrines of Mahayana Buddhism. Hiuen Tsang, the Chinese traveler who attended these events, confirms that Harsha used these grand platforms to establish the superiority of Mahayana Buddhism over other sects and religions, making the promotion of this specific faith the underlying reason for organizing such large scale religious assemblies.