Increase in concentration of the toxicant at successive trophic levels is known as

In agriculture,improper drainage of water leads to:
$I-$ The soil becomes waterlogged.
$II -$ The soil surface draws up salts from the water.
$III -$ Salts are deposited as a thin crust on the land surface.
$IV -$ Salts start accumulating around the roots of the plants.
$V -$ The increasing concentration of salts becomes favorable for crop growth.
$VI -$ It is highly beneficial for agriculture.
Which of the above statements are correct?

Which among the following is likely to have the highest levels of $D.D.T.$ depositions in its body?

Prolonged liberal irrigation of agricultural fields is likely to create the problem of

The major drawback of $DDT$ as a pesticide is that:

Give scientific reasons: Noise is also considered a part of air pollution.