Final answer:
Sarah is most likely to use quota sampling to ensure fair representation of all ethnicities in her sample.
Step-by-step explanation:
Sarah is most likely to use quota sampling to ensure that all ethnicities are fairly represented in her sample.
Quota sampling is a non-random sampling method where the researcher selects a predetermined number of individuals from each category or quota. In this case, Sarah can set quotas for each ethnicity and select individuals from each category until she reaches the required sample size.
By using quota sampling, Sarah can ensure representation of all ethnicities in her sample, even though it is not a probability sampling method.