By Pitting Two Species of Worms Against Each Other at Varying

By pitting two species of worms against each other at varying densities, researchers have determined that the zero growth isocline of species A is always above that of species B. This means that

A) species A will always exclude species B.
B) species B will always exclude species A.
C) one species will exclude the other, depending on the initial conditions.
D) both species will coexist at a lower density than either would alone.