Concept:A parameter is a numerical characteristic of a population.
Explanation:In statistics, a parameter describes a population (e.g., population mean, population variance).
A sample statistic describes a sample (e.g., sample mean).
The binomial distribution is a probability distribution, not a parameter.
Sample size is a property of a sample, not a population parameter.
Thus, population mean is an example of a parameter.
Answer:B. population mean.