What was the party affiliation of EMS Namboodiripad?

The correct answer is Option 4 - CPI(M)

E. M. S. Namboodiripad's party affiliation actually changed over his career. Here's a breakdown:

Early Years: He started with the Congress Socialist Party (CSP) in 1934.
Later Affiliation: He then joined the Communist Party of India (CPI).
Party Split: In 1964, the CPI underwent a split, and Namboodiripad became a key figure in forming the Communist Party of India (Marxist) (CPI(M)).
Therefore, depending on the specific time period, his party affiliation could be either CPI or CPI(M)