. A school-board administrator believes that the average number of days absent per year among students is less than 10 days. From past experience, he knows that the population standard deviation is 3 days. In testing to determine whether his belief is true, he could use one of the following plans:

i. n=100, a = 0.01

ii. n=75, a= 0.05

iii. n=50, a = 0.1

Which plan has the lowest probability of a Type II error, given that the true population average is 9 days?