Final answer:
Using rats from a single supplier for research results in a 'Convenience sample' which is not randomly selected, potentially leading to biased and unrepresentative results.
Step-by-step explanation:
Using rats from a single supplier for research equates to a c) Convenience sample, because the sample is chosen based on ease of access rather than being randomly selected from the entire population. Convenience samples are nonrandom and can lead to biased results because not all members of the population have an equal chance of being included. Unlike random samples, which require more effort to obtain, a convenience sample favors those outcomes that are more accessible to the researcher, resulting in a potentially unrepresentative and biased sample.