The correct answer is option 'D' - Finance Commission.

The Finance Commission is responsible for determining the central-state financial relations in India. It is an important constitutional body that plays a crucial role in the fiscal federalism of the country. Let's understand how the Finance Commission determines these relations:

1. Role and Composition of the Finance Commission:
- The Finance Commission is a constitutional body established under Article 280 of the Indian Constitution.
- It is a non-partisan and independent body that consists of a chairman and four other members appointed by the President of India.
- The members of the Finance Commission are usually experts in the fields of economics, public finance, and related disciplines.

2. Determining the Financial Relations:
- The main function of the Finance Commission is to make recommendations to the President on the distribution of financial resources between the central government and the state governments.
- It determines the principles and formula for sharing taxes, grants-in-aid, loans, and other financial resources between the center and the states.
- The recommendations of the Finance Commission are binding on the government and are implemented for a period of five years, known as the Finance Commission Award.

3. Factors Considered by the Finance Commission:
- The Finance Commission takes into account various factors while making its recommendations, such as the overall needs of the states, their population, area, backwardness, and fiscal capacity.
- It also considers the resources available to the center and the states, the impact of economic growth on the fiscal position, and the requirements of the central government.

4. Fiscal Devolution:
- One of the key functions of the Finance Commission is to recommend the share of states in the divisible pool of taxes, which includes both the revenue collected by the center and the states.
- This fiscal devolution aims to provide a fair distribution of resources to the states based on their needs and requirements.

5. Review and Monitoring:
- The Finance Commission also monitors the implementation of its recommendations and provides guidance to the central and state governments on matters related to fiscal management.

In summary, the Finance Commission is entrusted with the responsibility of determining the central-state financial relations in India. It considers various factors and makes recommendations on the distribution of financial resources between the center and the states. The recommendations of the Finance Commission are crucial in ensuring a fair and equitable fiscal federalism in the country.