The correct answer is C. Gulab Singh.
Gulab Singh was the last Sikh Governor of Kashmir. He was appointed as the Governor of Kashmir by Maharaja Ranjit Singh in 1819. He ruled Kashmir for 22 years, from 1819 to 1841. During his rule, he made many improvements in the administration of Kashmir. He also built many roads, bridges, and canals in Kashmir.
A. Maharaja Ranjit Singh was the founder of the Sikh Empire. He was not the Governor of Kashmir.
B. Sheikh Imam-ud-din was the Governor of Kashmir before Gulab Singh. He was appointed as the Governor of Kashmir by Maharaja Ranjit Singh in 1819. He ruled Kashmir for 2 years, from 1819 to 1821.
D. Ranbir Singh was the son of Gulab Singh. He succeeded his father as the Maharaja of Jammu and Kashmir in 1846. He ruled Kashmir for 32 years, from 1846 to 1878.