The correct answer is (a) Chitta Ranjan Das.
Aurobindo Ghosh was a Bengali polymath who was a nationalist, freedom fighter, philosopher, yogi, and spiritual teacher. He was one of the most important figures in the Indian independence movement.
In 1908, Ghosh was arrested and charged with conspiracy in the Alipur Bomb Case. He was defended by Chitta Ranjan Das, who was a leading lawyer and politician. Das gave a brilliant defense of Ghosh, and he was acquitted of all charges.
W.C. Bannerjee was a Bengali lawyer and politician who was also a member of the Indian National Congress. He was not involved in the Alipur Bomb Case.
Motilal Nehru was a Kashmiri Pandit lawyer and politician who was the father of Jawaharlal Nehru. He was not involved in the Alipur Bomb Case.
Tej Bahadur Sapru was a prominent Indian jurist and politician who was a member of the Indian National Congress. He was not involved in the Alipur Bomb Case.