Final answer:
The most desirable traits for a point estimator of a population parameter are minimum bias and minimum variance because they ensure accurate and consistent estimates. Therefore, the best choice among the given options is a. Minimum bias, minimum variance.
Step-by-step explanation:
When selecting a point estimator for a population parameter, the most desirable pair of traits for the estimator to have is minimum bias and minimum variance. This is because an estimator with minimum bias is on average correct when estimating the population parameter. An estimator with minimum variance produces results that are more consistently close to the population parameter, meaning the estimates have less spread around the true parameter value. Therefore, the best choice among the given options is a. Minimum bias, minimum variance.