The continuous, low-level extinction rate of species is sometimes called:

A) mass extinction.
B) minimal extinction.
C) selective extinction.
D) temporal extinction.
E) background extinction.

Background Extinction

The continuous, low-level extinction of species that has occurred throughout much of the history of life. Compare with mass extinction.

Continuous

A term used to describe a non-interrupted or unbroken series, sequence, or progression.

Low-Level

Referring to a minimal or reduced amount or degree in a given context.