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.