The correct answer is: B. Maharaja Hari Singh.
Maharaja Hari Singh was the ruler of the princely state of Jammu and Kashmir from 1925 to 1953. He signed the Instrument of Accession with India on October 26, 1947, making Jammu and Kashmir an integral part of India.
Maharaja Pratap Singh was the ruler of Jammu and Kashmir from 1846 to 1856. He was the son of Maharaja Gulab Singh, who founded the Dogra dynasty.
Maharaja Gulab Singh was the ruler of Jammu and Kashmir from 1846 to 1857. He was the founder of the Dogra dynasty.
Maharaja Ranjit Singh was the ruler of the Sikh Empire from 1799 to 1839. He was not a Dogra ruler.