Answer:
a. a different group of participants for each of the treatment conditions being compared
Step-by-step explanation:
Independent-Measures research design: This is one of the methods of research design that utilizes multiple or various experimental groups and only one experimental group posses participants. A single participant is supposed to be in only one condition of the IV i.e the independent variable in the experiment of the independent-measures research design.
In the question above, an independent-measures study uses a different group of participants for each of the treatment conditions being compared.