The correct answer is (a) N.M. Joshi.
N.M. Joshi was a pioneer of the trade union movement in India. He founded the All India Trade Union Congress (AITUC) in 1920. The AITUC is the largest trade union federation in India.
M.K. Gandhi was a nationalist leader who led the Indian independence movement. He was not involved in the trade union movement.
Lajpat Rai was a nationalist leader who was also involved in the trade union movement. He founded the Punjab Trade Union Congress in 1919.
Joseph Baptista was a trade union leader who was active in the early 20th century. He founded the Bombay Millhands Association in 1890.
N.M. Joshi was the first person to launch a trade union in the modern sense in India. He founded the AITUC in 1920. The AITUC is the largest trade union federation in India.