The correct answer is: A. Kanishka
The Third Buddhist Council was held in Kashmir in the 1st century CE, during the reign of the Kushan emperor Kanishka. The council was convened to discuss and resolve doctrinal disputes that had arisen in the Buddhist community. It also resulted in the standardization of the Buddhist canon.
Ashoka was a Mauryan emperor who ruled over most of the Indian subcontinent in the 3rd century BCE. He is considered one of the greatest rulers in Indian history, and is known for his promotion of Buddhism. However, he did not live during the time of the Third Buddhist Council.
Mahakashyapa was a Buddhist monk who was present at the First Buddhist Council, which was held shortly after the death of the Buddha. He is considered one of the most important figures in early Buddhism. However, he did not live during the time of the Third Buddhist Council.
Upali was a Buddhist monk who was present at the Second Buddhist Council, which was held about 100 years after the death of the Buddha. He is considered one of the most important figures in early Buddhism. However, he did not live during the time of the Third Buddhist Council.
Sabakarni was a Satavahana king who ruled over parts of southern India in the 2nd century CE. He is known for his patronage of Buddhism. However, he did not live during the time of the Third Buddhist Council.