Final answer:
The correct answer is (c) Adaptation / Genes, which refers to species evolving different traits or niches to reduce competition and coexist within the same geographic area.
Step-by-step explanation:
In the context of species coexisting within the same geographic area, character displacement can occur, where similar sympatric species evolve slightly different traits or niches to avoid complete exclusion from the area.
The answer to the student's question is (c) Adaptation / Genes, as species adapt by developing different genes that lead to varying traits that reduce direct competition.
Speciation can occur along two main pathways: allopatric speciation which is due to geographic separation and sympatric speciation which occurs without geographic barriers but through mechanisms such as behavioral isolation or polyploidy within a shared habitat.
Over time, these adaptations and the resulting reproductive isolation can lead to the formation of new species.