Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Whichof the following tests of a hypothesis concerning the population mean is mostappropriate?
Option A:A z-test if the population variance is unknown and the sample is small
Option B:A z-test if the population is normally distributed with a known variance
Option C:A t-test if the population is non-normally distributed with unknown variance and a small sample

Answer: B