Which of the Following Is True of Any One-Sample Experiment

Which of the following is true of any one-sample experiment?

A) We must know the population mean under the same condition of the independent variable as the one being tested.
B) We must know the population mean under some condition of the independent variable other than the one being tested.
C) We must know the sample mean under the condition of the independent variable being tested,but we do not need to know the population mean.
D) We must know the sample mean under the condition of the independent variable being tested and under some other condition of the independent variable.