Final answer:
a. have large fluctuations in population size. r-selected species are adapted to unstable environments, have large offspring numbers with little to no parental investment, leading to large population fluctuations. The correct answer is a. have large fluctuations in population size.
Step-by-step explanation:
r-selected species typically have large fluctuations in population size due to their adaptation to unstable and unpredictable environments. These species produce a large number of small offspring and do not invest in long-term parental care, meaning the offspring must be relatively mature and self-sufficient at birth. Examples of r-selected species include marine invertebrates like jellyfish and plants such as dandelions which produce wind-dispersed seeds.
Contrary to r-selected species are K-selected species, which live in stable and predictable environments, have fewer but larger offspring, and provide substantial parental care. An example of a K-selected species is the elephant, which has long lifespans, matures late, and invests significantly in the few offspring it has.
Thus, when considering the traits of r-selected species, the correct answer to the student's question is a. have large fluctuations in population size. They do not exhibit traits such as having long lives, being large-bodied, or having a high degree of parental investment in offspring, which are characteristic of K-selected species.