Case studies do not allow for replication. So, the correct option is (b).
Case studies are investigations that compile in-depth information about a person or group. They employ a wide range of research techniques, including observations, interviews, case studies, and personality tests, to collect the data. They can frequently collect both qualitative and quantitative data thanks to this. Research can be cross-sectional or longitudinal, which lasts for a long time.
It enables a researcher to thoroughly explore a subject. Case studies are unreliable because they cannot be duplicated and hence cannot be reliability tested. Any data acquired cannot be used to make generalisations because the outcomes are specific to the time, event, setting, and individual.
Learn more about Case studies here;
brainly.com/question/23179641
#SPJ9