Which of the following is true regarding extinction? a. single events or several causes working together to produce extinction in a short period is referred to as mass extinction. b. the rate of extinction is steady from clade to clade as are the number of species contained within a clade. c. if the rate of speciation in a clade is equal to or less than the rate of extinction, the clade will survive. d. extinction that occurs in a relatively short period of time is referred to as background extinction.

The answer is Letter A - Single events or several causes working together to produce extinction in a short period is referred to as mass extinction. 

Deforestation, illegal logging, pollution of the waters, burning plastics. These are just some of the examples that cause extinction to some of the endangered species. These situations happening all at once forces a group of an organism to decline.

The return of the wolf to yellowstone national park will probably affect the bird population to some degree, not significantly. while wolves will hunt birds when necessary, they prefer to hunt larger prey. the bird population will most likely only be affected when hunting is scarce for the wolves. birds of prey will also probably not be affected as much as other birds who spend more time on the ground hunting for food as the tend to spend more time in the air or in trees since they do not need to stay on the ground for long due to the nature of the way they hunt.