In laboratory experiments, two species of the protist Paramoecium were grown alone and in the presence of the other species. The following graphs show growth of species 1 (left) and species 2 (right), alone and when in mixed culture. Interpretation of these graphs shows that:

• A. competitive exclusion occurred in the these experiments.
• B. both species are affected by interspecific  competition but species 1 is less affected.
• C. both species are affected by interspecific competition but species 2 is less affected.
• D. both species are affected equally by interspecific competition.