Final answer:
In quasi-experimental studies, the exposure is not randomly assigned, and the subjects are exposed; thus, the correct option is 3) not randomly assigned, exposed.
Step-by-step explanation:
In quasi-experimental studies, the exposure of interest is not randomly assigned, and study subjects are exposed to exposure conditions. Therefore, the correct answer to the question would be option 3) not randomly assigned, exposed. Unlike true experimental designs where subjects are randomly assigned to either an experimental or a control group, in quasi-experimental designs, the researcher works with existing groups and does not randomly assign subjects to groups. This lack of random assignment means that researchers must take extra care in attempting to control for lurking variables that may skew results.