I need help with statistics hw.?

Question

A sample of n = 25 individuals is selected from a population with μ = 80, and a treatment is administered to the sample. Which set of sample characteristics is most likely to lead to a decision that there is a significant treatment effect?
a. M = 85 and large sample variance
b.M = 90 and small sample variance
c.M = 90 and large sample variance
d.M = 85 and small sample variance

Why is it B?

Answer 1

b is the most convincing.

90 is the value farthest from the mean, and a small sample variance indicates that it's unlikely that you just somehow ended up with an unusually high (or low) population.