The Partnership for Action on Green Economy (PAGE), a UN mechanism to assist countries transition towards greener and more inclusive economies, emerged at-

The answer is B. PAGE was launched in 2013 as a follow-up to the United Nations Conference on Sustainable Development (Rio+20) held in Rio de Janeiro in 2012. Its outcome document, 'The Future We Want', called for a green economy in the context of sustainable development and poverty eradication. PAGE was set up by UNEP, UNDP, ILO, UNIDO and UNITAR to help countries move towards greener economies.

Why the others fail:

• A mislabels the event. The 'Earth Summit' is the 1992 Rio conference. Johannesburg 2002 was the World Summit on Sustainable Development, which produced a Plan of Implementation but not PAGE.
• C is wrong. Paris 2015 (COP21) produced the Paris Agreement on climate change under the UNFCCC. It has no link to PAGE.
• D is invented. No such summit in New Delhi in 2016 gave rise to PAGE.

Core concept: the green economy as a development pathway, not just an environmental goal. This ties into GS-III (environment, inclusive growth, green jobs) and into India's own green growth and LiFE agenda, which is a good Mains angle on balancing growth with ecological limits.

Trap: students recall 'Earth Summit' and pick Johannesburg (A). The label belongs to Rio 1992, and the question asks about the 2012 Rio conference.