Four warbler species co-occur on the Mediterranean islands of Sardinia and Corsica.The four species' diets overlap,they each look similar,and they all utilize similar habitat.Upon closer investigation it appears that each species differentially uses zones within the habitat to forage.These species
A) Are interspecific competitors B) Could be interspecific competitors, but one needs experimental evidence to know if they are in fact competitors. C) Are not examples of niche differentiation. D) Are not examples of differential resource utilization.