The correct answer is (a). Asoka.
Asoka was the third emperor of the Mauryan Empire in India. He is known for his Buddhist reforms and his promotion of non-violence. He is also known for his many inscriptions, which provide valuable information about his reign and his empire.
One of Asoka’s inscriptions, the Lumbini pillar, is located at the site of the Buddha’s birth. The inscription states that Asoka visited Lumbini and erected a pillar to commemorate the Buddha’s birth. The inscription also provides a detailed description of the Buddha’s life and teachings.
The other options are incorrect. Kanishka was a Kushan emperor who ruled in the 2nd century CE. Harsha was an Indian emperor who ruled in the 7th century CE. Dharmapala was a Pala emperor who ruled in the 8th century CE. None of these emperors left inscriptions that mention the Buddha’s birth at Lumbini.