Explanation:

The objective of economic justice in the Indian Constitution is provided in the Preamble and the Directive Principles of State Policy.

1. Preamble:
The Preamble of the Indian Constitution outlines the objectives and ideals that the Constitution seeks to achieve. It states that India is a sovereign, socialist, secular, and democratic republic that aims to secure justice, liberty, equality, and fraternity for all its citizens. The term "socialist" in the Preamble signifies the commitment to economic justice and the redistribution of wealth and resources.

2. Directive Principles of State Policy:
The Directive Principles of State Policy (DPSPs) are a set of guidelines or principles given in Part IV of the Indian Constitution. Though not enforceable by the courts, these principles are fundamental in the governance of the country and provide guidance to the government in formulating policies and laws.

Several DPSPs are directly related to economic justice, some of which are:

- Article 38: It directs the State to secure a social order for the promotion of the welfare of the people. It emphasizes that the State should minimize inequalities in income and strive to eliminate inequalities in status, facilities, and opportunities.
- Article 39: It includes various provisions related to economic justice, such as securing the right to an adequate means of livelihood, equal pay for equal work, protection of workers, and distribution of resources to prevent concentration in a few hands.
- Article 41: It directs the State to provide public assistance, within the limits of its economic capacity, to ensure the right to work, education, and public assistance in cases of unemployment, old age, sickness, and disablement.
- Article 42: It emphasizes the need for just and humane conditions of work and maternity relief.
- Article 43: It directs the State to secure a living wage, decent standard of life, and social and cultural opportunities for workers.

These DPSPs reflect the commitment of the Indian Constitution towards economic justice and the well-being of its citizens. While they may not be legally enforceable, they serve as a guiding framework for the government to formulate policies and laws that promote economic justice in the country.

Therefore, the correct answer is option B: the Preamble and the Directive Principles of State Policy.