India became a party to convention on biological diversity in

The Earth Summit of Rio de Janeiro, also known as the United Nations Conference on Environment and Development (UNCED), was held in Rio de Janeiro from 3 to 14 June 1992. It resulted in the Convention on Biodiversity, a multilateral treaty. Three major goals were addressed in this convention which included: conservation of biodiversity; sustainable use of its components; and the fair and equitable sharing of benefits arising from the genetic resources. India became a party to Convention on Biological Diversity in '1994'.

So, the correct answer is '1994'.