Answer:
The kind of sampling the researcher is using is Convenience sampling method.
Step-by-step explanation:
Convenience sampling is a kind of non probability sampling. A non probability sampling is a type of sampling where the probability of selecting a sample is not defined.
In case of convenience sampling the researcher targets the population nearest to him/her or the quite accessible population. For example, sampling done at a shopping mall or a college campus.
There are no other conditions applied while conducting a convenience sampling. The only criteria is that the participants are willing to participate. For this too the researcher can offer to pay certain amount to the participants so that they participate in the research.
In the provided problem the researcher samples preschool students at a local daycare center. He also pays $10 for each participation.
This is an example of Convenience sampling method.