Explanation

All four are recognised sources of law in India: the Constitution of India is the supreme law; statutes are laws enacted by Parliament and State legislatures; customary law (long-standing community customs) is recognised where not inconsistent with statute; and case law — judicial precedents under Article 141 (Supreme Court decisions binding on all courts) — is a major source. Hence options 1, 2, 3 and 4 are all sources — option D.