The Phoenix area of the Southwestern desert typically receives 8 inches of precipitation yearly, in two seasonal patterns. Even though it is an arid region, it has high biological diversity. Thin-leaf trees abound, such as palo verde and desert ironwoods. Wide varieties of cactus thrive, including the cholla, p-r-i-c-k-l-y pear, and saguaro. Wildlife includes insects, reptiles, many bird species, small rodents, and other mammals. Which element in the Southwestern desert ecosystem is abiotic?
A. Populations can have negative effects on their environment.
B. Populations can affect the size of other populations.
C. Populations have no effect on their environment.
D. Populations can adapt to changes in the environment.