Answer:
Convenience/random assignment.
Explanation:
Convenience sample: This is a non-probability and non-random sampling technique, in which subjects are being selected because of their proximity and convenient accessibility to the researcher or experimenter. Also known as availability sampling, used to create an easily accessible sample, availability at a given time, and ready to be a part of the given sample.
Random assignment: Also known as random placement. This is an experimental technique used to assign animal subjects or human participants to distinct groups in the experiment (for example, a control group versus a treatment group) using randomization, such as by a random number generator or by a chance procedure.