The correct answer is option-1, Finance Commission. A constitutional body as per the Indian Constitution is an institution that is mentioned and provided for in the Constitution itself. This means that the body has legal and constitutional status. The Finance Commission is one such body. It is a statutory body created by Article 280 of the Constitution of India. Its main responsibility is to recommend the distribution of financial resources between the central government and the state governments. The Finance Commission is composed of a chairman and four other members appointed by the President of India. It plays a crucial role in ensuring financial decentralization and fiscal federalism in the country. Options 2 and 3, National Development Council and Planning Commission, are not constitutional bodies as they were not mentioned or provided for in the Constitution. Therefore, the correct answer is option-1.