In a single blind study, the participant to which group he or she has been assigned, and the researcher to which group each participant has been assigned.

is unaware; is aware

Explanation:

Single bind study: In psychology, the term "single-blind study" is described as one of the different research methods that involve a particular research procedure whereby the researchers or the experimenters don't tell the subjects or participants whether they're being provided with a control treatment or a test treatment.

Example: In a single-blind study, participants don't know whether they're taking a placebo or experimental drug.