The correct answer is C. Kanishka.
Kanishka was a Kushan emperor who ruled over a vast empire in Central Asia and the Indian subcontinent from around 127 to 150 CE. He was a great patron of Buddhism and Hinduism, and he built many temples and monasteries throughout his empire. Kanishkapura was one of his capital cities, and it was located in what is now the city of Peshawar in Pakistan.
Ashoka was a Mauryan emperor who ruled over most of the Indian subcontinent from around 272 to 232 BCE. He was a great conqueror, but he is also known for his Buddhist reforms and his promotion of non-violence. He did not build Kanishkapura.
Nagarjuna was a Buddhist philosopher who lived in the 2nd century CE. He is considered one of the founders of Mahayana Buddhism, and he is known for his writings on Madhyamaka philosophy. He did not build Kanishkapura.
Vasugupta was a Kashmiri Shaivite philosopher who lived in the 9th century CE. He is considered the founder of the Pratyabhijna school of Kashmir Shaivism, and he is known for his writings on the nature of consciousness. He did not build Kanishkapura.