Assume that the time patients spend waiting to see the doctor in the polyclinic is normally distributed. A random sample of 5 observations give the following sample statistics --- sample mean = 30 minutes and sample variance = 86. Suppose the population variance is unknown, what is the 90% confidence interval of the population mean?

A.21.16 38.84

B.19.93 35.66

C.19.55 37.1

D.18.40 32.97