The correct answer is option 3, 1986. The Environment (Protection) Bill was passed by the Parliament of India in 1986. This bill aimed to protect and improve the quality of the environment in India.

Option 1, 1984, is incorrect because the bill was not passed in that year.

Option 2, 1972, is incorrect because the Environment (Protection) Bill was not passed by the Parliament of India in 1972. However, the government did take some steps towards environmental protection in 1972 by establishing the Department of Environment.

Option 4, 1981, is incorrect because the bill was not passed in that year.

The correct answer is option 3, 1986, as it accurately represents the year when the Environment (Protection) Bill was actually passed by the Parliament of India.