To conduct an appropriately randomized experiment, Hiya should aim for a population that is specific enough to control for variables that might influence the outcome while still being broad enough to ensure generalizability of the results.
Among the options provided:
A. Dogs in California: This population includes a diverse range of breeds, sizes, and backgrounds, and while it is geographically specified, it may introduce too many variables.
B. Golden retrievers in Omaha, Nebraska: This population is more specific (focusing on one breed in a specific location), which could allow for more control over genetic and environmental factors, but it may limit the generalizability of findings only to golden retrievers in that area.
C. Poodles in the United States: This population is broader than option B, allowing for more generalizability, but still focuses on a specific breed.
Based on the goal of conducting a randomized experiment while balancing specificity and generalizability, Population #2: golden retrievers in Omaha, Nebraska, would allow for a controlled environment for the study, though it is limited to that specific breed and location. If the aim is purely to randomize the experiment effectively, involving breed-specific traits, then option B is the best choice among the three. However, if generalizability of results is also a key consideration, option C could be more favorable.
Ultimately, for a randomized experiment that can effectively study the effect of diet on activity level while managing variability, Population #2 is probably the most suitable choice.