Correct Option (C):
Assertion (A) is true. Harshavardhana, a prominent ruler of the 7th century CE, is historically known to have convened the Prayag Assembly (also known as the Mahamokshaparishad) at Prayag (modern Allahabad). This was a quinquennial (every five years) grand religious congregation where he distributed wealth and gifts to ascetics, Brahmins, and the poor, irrespective of their religious affiliations.
Reason (R) is false. While Harshavardhana was a patron of Mahayana Buddhism, the Prayag Assembly was not convened solely to popularize this form of Buddhism. Historical accounts, particularly those of Xuanzang, indicate that the assembly's purpose was broader, encompassing acts of charity, religious harmony, and reverence for various deities and religious figures, including the Buddha, Surya (Sun God), and Shiva. The distribution of wealth was extended to all religious sects, demonstrating a policy of broad religious patronage rather than exclusive promotion of Mahayana Buddhism. Therefore, the statement that he wanted to popularize only the Mahayana form of Buddhism is factually incorrect.
Incorrect Options:
Option (1) is incorrect because Reason (R) is false.
Option (2) is incorrect because Reason (R) is false.
Option (4) is incorrect because Assertion (A) is true.