Which of the following is not entirely true fact?
(a) Competition occurs when closely related species compete for the same resources that are limiting
(b) Totally unrelated species could compete for the same resource
(c) Resources need to be limiting for competition to occur; in interference competition, the feeding efficiency of one species might be reduced to the interfering and inhibitory presence of the other species, even if resources are plenty
(d) A complex interplay of interspecific interactions and environmental variability characterizes community structure