Before the establishment of NITI Aayog, how long did the Planning Commission operate?

65 years

The correct answer is Option 4 - 65 years

The Planning Commission operated for about 65 years before it was replaced by NITI Aayog in 2015. It was established in March 1950 and continued until December 2014.

The Planning Commission was set up in March 1950 by a simple resolution of the Government of India. The Prime Minister was its Chairperson.
The Government of India replaced the Planning Commission with a new institution named NITI Aayog. NITI Aayog stands for National Institution for Transforming India. The NITI Aayog came into existence on 1 January 2015.