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

The galapagos island contain 13 species of finches four of the species are seen here it is believed that all of the species had one common ancestor and overtime

The mixture of sperm and fluids from the seminal vesicles, prostate gland, and cowper's glands is called

Ascientist is investigating the effects of salinity on fish development. he places fertilized fish eggs in an aquarium that contains low salinity and observes their development. what factor would improve experimental design the most? place the fish eggs in the open ocean because that is the natural habitat include another aquarium that has normal salinity to compare to the low salinity aquarium include an aquarium that replaces salt with sugar to confirm that the effects are specific to salt grow algae with the fish eggs in order to provide adequate nutrients to the developing embryos