The correct answer is: C. Raja Lalitaditya
The Shankaracharya temple at Srinagar was built by Raja Lalitaditya Muktapida, a Kashmiri king of the Karkota dynasty. He ruled from 724 to 761 CE and is considered to be one of the greatest rulers of Kashmir. The temple is dedicated to Adi Shankaracharya, a Hindu philosopher and theologian who lived in the 8th century CE. It is one of the most important temples in Kashmir and is a popular pilgrimage destination.
Raja Vikramaditya was a legendary king of Ujjain who is said to have ruled in the 5th or 6th century CE. He is known for his military conquests and his patronage of the arts and sciences. There is no historical evidence to suggest that he built the Shankaracharya temple at Srinagar.
Raja Gopaditya was a king of Kashmir who ruled in the 8th century CE. He is known for his construction of several temples and other public works projects. However, there is no evidence to suggest that he built the Shankaracharya temple at Srinagar.
Therefore, the correct answer is Raja Lalitaditya.