Overcrowding in a population does not result in

Analyze the question: We are asked which outcome overcrowding does not cause. Overcrowding means too many individuals of a species share limited resources such as food, water, space and mates.

Explain the concept: When a population becomes too dense, these things happen:

• Competition (C): Individuals compete for limited food, space, and mates. This is intraspecific competition.
• Death (A): Starvation, disease spread, and stress raise the death rate.
• Migration (D): Some individuals leave to find better resources (emigration).

Commensalism (B) is different. It is a symbiotic relationship between two different species in which one benefits and the other is neither helped nor harmed. Examples are an orchid growing on a tree, or the remora fish traveling with sharks. It does not arise because of overcrowding. It is an interaction between species, not a consequence of too many individuals of one species.

Step by step:

1. Overcrowding → scarce resources → competition (happens).
2. Competition and stress → death (happens).
3. Poor conditions → some individuals migrate (happens).
4. Commensalism → an association between different species, not caused by overcrowding (does not happen as a result).

**Answer: B. Commensalism.

Tip: In "does not result in" questions, first list what overcrowding does cause: competition, disease, death, migration, and reduced birth rate. The odd one out, which here is a type of species relationship, is your answer.