Each of 20 students in a freshman physics lab is assigned to perform an experiment to measure the speed of light, collect 100 measurements, and construct a 0.90 confidence interval for the true speed. Which of the following R expressions best represents the probability that at least 18 of these confidence intervals will cover the true speed? Why?

(a) 0.90 (b) 1 - 0.102 (c) 1-pnorm (18,mean=18,sd=sqrt (20) *. 3) (d) 1-pbinom (17,size=20 ,prob=.9) (e) pbinom(18,size=100,prob=.9)