Which simple ecological concept best explains why resistant organisms can colonize after antibiotic therapy?

• A. Antibiotics create magnetic gradients in mucosal surfaces that physically attract resistant organisms while repelling commensals, driving colonization by magnetotaxis.
• B. Resistant organisms are always the fastest growing regardless of niche availability, so antibiotics have no role in shifting community composition by competition.
• C. Removal of competitors opens unoccupied niche space and resources (competitive release), enabling resistant taxa to expand because they face less competition.
• D. Antibiotics create new chemical energy in the gut that exclusively feeds resistant organisms and not commensals, producing colonization advantages unrelated to competition.

Answer: (C)