Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

     The world above the forest floor can be observed by all of US. Rarely, however, do we take the time to notice the teeming life and bustling activity that occurs beneath the ground we walk on.

     Of all soil-dwelling creatures, the most abundant are mites and springtails, insect-like creatures that literally eat their way through caverns of subterranean vegetation. The tiny, eight-legged mites lay their eggs on plant matter, which their larvae eat and convert into fresh soil. The bright-colored springtails are named for their ability to leap long distances during their search for decomposed plant matter to eat.

     Both mites and springtails are prey to a host of soil-dwelling predators. They thus anchor one end of the food chain that extends to higher forms of forest "lowlife", such as moles that feed on earthworms and shrews that eat beetles.

     Those mammals, in turn, dig tunnels that function as underground byways for other subterranean species. Hibernating chipmunks, turtles, and salamanders sift and mix the soil when they burrow to winter dens. Cottontails and gray foxes excavate shallow dens as sanctuary from predators and harsh weather, while gray squirrels, hiding acorns for the lean season, further blend the earth. From microbe to people, thousands of species work the land upon which all life depends.

According to the passage, which of the following are the most numerous inhabitants of the soil?