Why do you think species remain in a stage of stasis?
a. a stable ecological niche leads to absence of selection pressure, which in turn causes species to remain unmodified or in stasis.
b. an unstable ecological niche leads to various selection pressures, which in turn causes the species to remain in a stage of stasis.
c. a stable ecological niche leads to various selection pressures, which in turn causes species to remain unmodified or in stasis.

The answer is A. A stable ecological niche leads to the absence of selection pressures, which in turn causes species to remain unmodified or in stasis. This can be simplified with an example: If there are just enough lions on an island and just enough buck for both species to survive without the lions starving or the buck being killed off, neither of the species would have to adapt to survive because their predator-prey relationship is stable. This means that they can continue to live in this state of stasis or equilibrium.