Answer:
D. purposive sampling
Explanation:
Purposive sampling: The term purposive sampling is also referred to as subjective, selective, or judgment sampling. The purposive sampling technique involves the researcher or experiment to rely on his or her own decision or judgment while choosing the members of a particular population to participate in his or her study. This is one of the non-probability sampling method.
In the question above, Dr. Jenning's is using purposive sampling.
If its an Apex question, add options next time.
A small portion of the virus itself mixed with the componentes of the vaccine
