Some scientists think humans are living in the period of the next mass extinction. There are two ways extinctions can occur. What is the difference between the two kinds of extinctions? A. A mass extinction occurs slowly and eliminates one species. Background extinction occurs quickly and kills many species.
B. A mass extinction occurs quickly and kills many species. Background extinction occurs slowly and eliminates one species.
C. A mass extinction occurs from competition for available niches, and a background extinction occurs from a large, natural cause.
D. A mass extinction occurs due to slow environmental changes, and a background extinction occurs due to a rapid, widespread environmental event.