The Preamble to the Constitution of India is

The correct answer is D. The Preamble is part of the Constitution, as the Supreme Court held in Kesavananda Bharati (1973), overruling Berubari Union (1960), which had said it was not. But it has no independent legal effect. It cannot by itself create an enforceable right or limit legislative power. Courts use it mainly as an aid to interpreting ambiguous provisions.

Why the others fail:

• A is wrong because it says the Preamble has no legal effect at all. Its ideals guide interpretation, and the Court has relied on its wording while reading the basic structure.
• B is wrong on status. Berubari's view that the Preamble is not part of the Constitution no longer holds.
• C is wrong because the Preamble does not carry the same effect as an operative article. Enforceable rights come from Part III and directive principles from Part IV.

Mains angle: the Preamble reflects the constitutional philosophy of the state. The 42nd Amendment (1976) added 'socialist', 'secular' and 'integrity', and Kesavananda held that the Preamble can be amended under Article 368, provided the basic structure is not altered.

Trap: candidates pick A because 'no legal effect' sounds absolute. The key phrase in D is 'independently of other parts'.