2. which one of the following interspecies relationships has a negative effect on the abundance of both species?
a predation
b competition
c commensalism
d parasitism

Hello.

The correct answer you are looking for is B. competition. The process of competing for resources, such as food, could and most likely would result in either the endangerment of a species, or an extinction. In your case, competition is the act of interactions between organisms, in which birth, growth and death depend on gaining a share of a limited environmental resources. Thus, competition proves to be a negative affect on an abundance of 'both species.'

D.) domain, kingdom, phylum, class, order, family, genus, species