Answer:
A. convenience sample
Explanation:
This is an example of a convenience sample because the researcher has simply asked the first 10 people he meets at a shopping mall. The individuals in the sample were not randomly selected from the population of people who use the brand of shampoo. The researcher may have simply chosen the first 10 people he encountered because they were readily available and easy to access. Therefore, this sample is not necessarily representative of the entire population of people who use the brand of shampoo, and the results of the study may not be reliable or generalizable to the larger population.