The correct answer is: A. Sena Raja
Sena Raja was the founder of the Keonthal state in 765 AD. He was a Rajput prince who came from the Garhwal region of India. He founded the state after defeating the local ruler, Raja Girisen. Sena Raja was a wise and just ruler, and he is remembered as one of the greatest rulers of the Keonthal state.
Raja Girisen was the ruler of the Keonthal state before Sena Raja. He was a cruel and unjust ruler, and he was eventually overthrown by Sena Raja.
Raja Ranjit Singh was a Sikh ruler who lived in the 18th century. He was the founder of the Sikh Empire, and he is considered to be one of the greatest rulers of India. However, he did not found the Keonthal state.
Therefore, the correct answer is: A. Sena Raja