To solve this problem, we need to identify the year in which the historic Convention on Biological Diversity, known as 'The Earth Summit,' was held in Rio de Janeiro.$\newline$Let's analyze the options provided:$\newline \bullet$Option 1: 1985$\newline$ - The Earth Summit was not held in 1985. This option is incorrect.$\newline \bullet$Option 2: 1992$\newline$ - The Earth Summit, officially known as the United Nations Conference on Environment and Development (UNCED), was indeed held in Rio de Janeiro in 1992. This option is correct.$\newline \bullet$Option 3: 1986$\newline$ - The Earth Summit was not held in 1986. This option is incorrect.$\newline \bullet$Option 4: 2002$\newline$ - The Earth Summit was not held in 2002. This option is incorrect.$\newline$Therefore, the correct answer is Option 2: 1992.