D.

1,2

A lake near a village suffered heavy mortality of fishes within a few days, because lots of urea and phosphate fertilizer were used in the crops in the vicinity and the area was sprayed with DDT by an aircraft, Inorganic phosphorus and nitrogen are responsible for the growth of algae. In polluted water these increase due to which algae increase greatly at the surface of water forming water bloom. Due to death of these algae, their organic matter gets decomposed due to which oxygen gets depleted and aquatic animals die.

D.

forest

Forest is renewable, exhaustible natural resource. Renewable resources are living, able to reproduce or replace themselves and to increase. The renewable resources get replenished, recycled or reproduced and can fast forever provided they are not used beyond their renewability. The exhaustible resource is the natural resources with finite stock or supply, they are vulnerable to both qualitative and quantitative degradation.
Coal and petroleum are non- renewable and exhaustible natural resources.
Minerals are renewable and inexhaustible natural resources.

C.

death of fish due to lack of oxygen

A river with sewage increases the organic waste and decreases the dissolved oxygen.

A.

Gases like sulphur dioxide

Scrubber is an electrostatic precipitator in which the dirty air is cleaned by capturing the gas like SO₂ and other oxides in water/lime spray

C.

Oceans

The atmosphere is the source of carbon dioxide, which is utilised by plants in photosynthesis reduced to form carbon compounds. The total mass of carbon currently in the atmosphere is about 7 x 10¹⁷ g, ie, 700000 million tonnes Oceans regulate the CO₂ content in the atmosphere and thus play a very important role. Sea water contains 50 times more CO₂ than air, ie, about 70 % of total global carbon is found in oceans. This is in the form of carbonates and bicarbonates.