The correct answer is (a). Alfred Park at Allahabad has been renamed after Bhagat Singh.
Bhagat Singh was an Indian revolutionary who was hanged by the British government in 1931 for his role in the assassination of a British police officer. He is considered a martyr in India and is one of the most popular freedom fighters in the country.
The park was renamed in his honor in 1992. The renaming was part of a larger effort to commemorate the contributions of Indian freedom fighters.
The other options are incorrect. Chandra Shekhar Azad was another Indian revolutionary who was also hanged by the British government. Subhash Chandra Bose was an Indian nationalist who led the Indian National Army against the British. Motilal Nehru was a prominent Indian lawyer and politician who was the father of Jawaharlal Nehru, the first Prime Minister of India.