Suppose that on a hypothesis test for a single population mean, $H\_{a}:\textbackslash{} \mu\textbackslash{} \lt\textbackslash{} 10$. Assume that $H\_{a}$~is true. For a fixed sample size and significance level $\alpha$, the power of the test will be greatest if the actual mean is which of the following? 
选项为:A:$$8$$  B:$$9$$  C:$$10$$  D:$$11$$  E:$$13$$  请回答其中一个选项.