Concept:A constitutional body is a body established by the Constitution of India itself, with its powers and functions clearly defined in a specific Article of the Constitution.
Explanation:First, identify the body that is created directly by the Indian Constitution. The Election Commission of India (ECI) is established under Article 324 of the Constitution. This article gives it the authority to conduct free and fair elections to the Parliament, State Legislatures, and the offices of the President and Vice-President. Therefore, it is a constitutional body.
Second, check the nature of the other options. NITI Aayog is a policy think tank established by the government in 2015, not by the Constitution. The National Human Rights Commission (NHRC) is a statutory body created under the Protection of Human Rights Act, 1993, not by the Constitution. The Central Bureau of Investigation (CBI) is an investigative agency under the Ministry of Personnel and is also not a constitutional body. Only the Election Commission of India fulfills the condition of being a constitutional body.
Answer:Election Commission (Option C)