The correct option is D
It is an integral part of the constitution, but it is neither a source of power to the legislature nor a prohibition upon the powers of the legislature.
Explanation:
Option (a) is incorrect: Since Keshavanand Bharti case (1973) and LIC of India case (1995), the Supreme Court held that the preamble is an integral part of the constitution. However, It is non-justiciable, that is, its provisions are not enforceable in courts of law.
Option (b) is incorrect: Preamble acts as a torchbearer for the interpretation of the constitution, but It is an integral part of the constitution.
Option (c) is incorrect: It is an integral part of the constitution, but it is neither a source of power to the legislature nor a prohibition upon the powers of the legislature.
Option (d) is correct: It is an integral part of the constitution, but it is neither a source of power to the legislature nor a prohibition upon the powers of the legislature.