Factors like lack of variation and environmental changes can cause a species to fail to survive. this is known as
a. conservation.
b. evolution.
c. extinction.
d. mutation.

The correct answer for the fill in the blank is c) Extinction.

Extinction refers to the termination of a group of organisms or species that results due to various factors like change in the environmental conditions that does not allow the species to adapt. In other words, when species become extinct, it represents the death of the last individual of that species so that it is nowhere found in the world.

Therefore, when factors like lack of variation and environmental changes result in failure of survival, it represents extinction.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.