The fast unto death by Potti Sreeramulu in 1952 played a crucial role in:

The correct answer is: a) The formation of the linguistic state of Andhra.

Potti Sreeramulu was an Indian independence activist who fasted unto death in 1952 to demand the formation of a separate Andhra state for Telugu-speaking people. His death led to widespread protests and the eventual formation of the state of Andhra Pradesh in 1956.

The other options are incorrect because:

• Option b) is about the abolition of the zamindari system, which was a system of land tenure in India that was abolished in 1950.
• Option c) is about the Gandhi-Irwin Pact, which was a pact signed in 1931 between Mahatma Gandhi and Viceroy Lord Irwin.
• Option d) is about the Telangana armed struggle, which was an armed conflict that took place in the Telangana region of India from 1946 to 1951.