Directive Principles of State Policy (DPSP) are a set of guidelines or principles given in Part IV of the Indian Constitution. These principles are not enforceable by the courts, but they serve as a moral and political compass for the government to follow in its policy-making and legislative processes. The correct answer is option 'D', which states that Directive Principles promise equal income and free health care for all Indians. Let's understand why this is not a correct description.

Directive Principles are not enforceable by the courts:
- One of the key features of Directive Principles is that they are not enforceable by the courts. Unlike fundamental rights, which are justiciable and can be enforced through legal remedies, Directive Principles are non-justiciable and cannot be enforced by the courts of law. This means that individuals cannot approach the courts for the enforcement of DPSPs.

Directive Principles have a political sanction:
- While Directive Principles may not be enforceable by the courts, they have a political sanction. This means that they provide a framework for the government to formulate policies and laws. The government is expected to take these principles into consideration while making laws and policies, although they are not legally bound to do so.

Directive Principles are declarations of objectives for State Legislation:
- Directive Principles are indeed declarations of objectives for the state legislation. They provide guidance to the government in formulating laws and policies that promote the welfare of the people, social justice, economic equality, and the overall development of the country. They cover a wide range of areas such as education, health, agriculture, labor rights, and environmental protection.

Directive Principles do not promise equal income and free healthcare for all Indians:
- The Directive Principles do not promise equal income and free healthcare for all Indians. While they emphasize the need for reducing inequalities and providing adequate healthcare facilities, they do not guarantee equal income or free healthcare. These principles aim to establish a welfare state and create conditions for the equitable distribution of resources, but the actual implementation of policies in these areas is left to the discretion of the government.

In conclusion, the correct description of Directive Principles of State Policy is that they are not enforceable by the courts, they have a political sanction, and they provide objectives for state legislation. However, they do not promise equal income and free healthcare for all Indians.

* Article 37, while stating that the Directive Principles are not enforceable in any court of law, declares them to be "fundamental to the governance of the country" and imposes an obligation on the State to apply them in matters of legislation.