Which Statement About Zero Population Growth Isoclines of Two Competing

Which statement about zero population growth isoclines of two competing species is true?

A) Species coexistence requires that the two isoclines cross.
B) The crossing of the two isoclines is a sufficient condition for species coexistence.
C) If the species coexist, they will each do so at a higher density than either would if placed alone.
D) Strongly competing species can only coexist if the two species have very different carrying capacities.