Which one of the following Directive Principles was inserted by the Constitution (42nd Amendment) Act, 1976?

The Constitution (42nd Amendment) Act, 1976, added four new Directive Principles of State Policy (DPSP) to the Indian Constitution. These include Article 39 (securing opportunities for healthy development of children), Article 39A (promoting equal justice and providing free legal aid to the poor), Article 43A (participation of workers in management of industries), and Article 48A (protection of environment and wildlife) [1]. Among the given options, 'Equal justice and free legal aid' was specifically inserted by this amendment [1]. Other options were added or modified by different amendments: the requirement to 'minimise inequalities in income' (Article 38) was added by the 44th Amendment Act of 1978 [1][2], 'Promotion of co-operative societies' (Article 43B) was inserted by the 97th Amendment Act of 2011, and 'early childhood care' (Article 45) was modified by the 86th Amendment Act of 2002.

Sources

1. [1] Indian Polity, M. Laxmikanth(7th ed.) > Chapter 9: Directive Principles of State Policy > NEW DIRECTIVE PRINCIPLES > p. 110
2. [2] Introduction to the Constitution of India, D. D. Basu (26th ed.). > Chapter 9: Directive Principles of State Policy > DIRECTIVE PRINCIPLES OF STATE POLICY > p. 179