The correct answer is: A. Maharaja Ranbir Singh.
Maharaja Ranbir Singh was the second Maharaja of Jammu and Kashmir. He was born in 1830 and ascended the throne in 1857 after the death of his father, Maharaja Gulab Singh. He ruled until his death in 1885.
Maharaja Ranbir Singh was a strong and capable ruler. He expanded the territory of Jammu and Kashmir, and he also introduced many reforms, including the establishment of a modern education system and the construction of roads and bridges. He was also a patron of the arts and literature.
Maharaja Ranbir Singh was succeeded by his son, Maharaja Pratap Singh.
Option B is incorrect. Maharaja Hari Singh was the third Maharaja of Jammu and Kashmir. He ascended the throne in 1925 after the death of his father, Maharaja Pratap Singh. He ruled until 1947, when he signed the Instrument of Accession, making Jammu and Kashmir a part of India.
Option C is incorrect. Maharaja Ranjit Singh was the founder of the Sikh Empire. He was born in 1780 and ruled from 1799 until his death in 1839. He was a powerful and successful ruler, and he expanded the Sikh Empire to include much of the Punjab region.
Option D is incorrect. Yuvraj Karan Singh was the son of Maharaja Hari Singh. He was born in 1924 and served as the Regent of Jammu and Kashmir from 1947 to 1953. He was also the first Chief Minister of Jammu and Kashmir from 1953 to 1964.