Explanation:

- Option 1: E M S Namboodiripad

- He was the first Chief Minister of Kerala.

- Elected in 1957, he led the first democratically elected communist government in the world.

- Option 2: Pattom A Thanu Pillai

- He was the second Chief Minister of Kerala from 1960 to 1962.

- Also served as Governor in various states.

- Option 3: R Shankar

- Served as Kerala’s Chief Minister from 1962 to 1964.

- Was part of the Indian National Congress.

- Option 4: C Achutha Menon

- He became Chief Minister after R Shankar, serving from 1969 to 1970 and again from 1970 to 1977.

- Belonged to the Communist Party of India.