Paramecium bursaria coexisted because:
“Partitioned resources” for paramecium bursaria coexisted because. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. A niche is the multidimensional set of abiotic conditions, resources, and biotic relationships under which a population can persist. The fundamental niche reflects physiological and resource limits, while the realized niche is modified by competitors, consumers, mutualists, and dispersal barriers. The remaining alternatives—“Faster reproduction”, “No competition”, “Predatory”—refer to
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 13