(A) Planning Commission
NITI Aayog (National Institution for Transforming India) replaced the Planning Commission, which was established in 1950 and dissolved in 2014.
The source passages do not cover NITI Aayog directly, but this is a standard CBSE Economics/Social Science fact. The Planning Commission was the preceding government body replaced by NITI Aayog on 1 January 2015. The other options — Election Commission, UGC, and UPSC — are independent constitutional/statutory bodies with entirely different functions. Examiners expect the student to directly identify option (A).