The idea that older, more stable habitats have greater species richness than habitats subjected to ...

The idea that older, more stable habitats have greater species richness than habitats subjected to
  frequent, widespread disturbances is known as:
  a. natural selection.
  b. the time hypothesis.
  c. island biogeography.
  d. the theory of community stability.
  e. the disturbance hypothesis.

Question 2

Ecologist James H. Brown of the University of New Mexico has addressed species composition and
  richness in experiments conducted since 1977 in the Chihuahuan desert of southeastern Arizona. In
  one experiment, the removal of three dominant species, all kangaroo rats, from several plots resulted in
  an increased diversity of other rodent species. This increase was ascribed both to lowered competition
  for food and also to an altered habitat, because the abundance of grass species __________ after the
  removal of the kangaroo rats.
  a. increased
  b. decreased
  c. did not change
  d. was threatened
  e. shrunk