At the inferior end of the trachea is an internal ridge of mucosal covered cartilage that initiates a cough reflex when it is stimulated; this structure is the

Agene pool: a) is the collection of all the alleles found in a single species b) is the collection of all the alleles found in a single population c) is the collection of all the chromosomes found in a single population d) is the collection of genes in a species that allow the individuals to swim