Any undesirable change in physical, chemical or biological characteristic of air, land, water or soil is called

The correct option is D Pollution
Biomagnification
Biomagnification refers to the process in which the accumulation of toxic substances within organisms increases at each trophic level on progressing the successive levels of the food chain. This is due to the fact that certain toxicants cannot be metabolised or excreted by the living body and hence, goes on accumulating in the tissues.

Population explosion
Population explosion refers to the increase in population drastically within a short time period.

Pollution
Undesirable changes including physical, biological or chemical to the environment causing various adverse effects is called pollution. These changes affect characteristics of air, water, land or soil.

Eutrophication
The aging of water bodies due to the increase in the concentration of nutrients like phosphates, nitrates etc. is called eutrophication.