Which one of the following pairs is mismatched?

Which of the following changes would be likely to make terrestrial life on this planet impossible?

Write critical notes on the following:
$(a)$ Eutrophication
$(b)$ Biological magnification
$(c)$ Groundwater depletion and ways for its replenishment

The Government of India passed the Environment (Protection) Act in the year $............$.

When did the worst environmental nuclear power plant accident and the $MIC$ gas tragedy occur,respectively?

Consider the following reasons for the massive fish mortality observed in a lake near a village within a few days:
$(1)$ Excessive use of urea and phosphate fertilizers in nearby crops.
$(2)$ Spraying of $DDT$ using aircraft.
$(3)$ The lake water turned green and foul-smelling.
$(4)$ Initial decrease in phytoplankton in the lake leads to a maximum decrease in photosynthesis.
Which of the above reasons are responsible for the massive fish mortality?