Here are three studies:
a: june asks eight of her friends if they plan on buying a school lunch that day.
b: sam selects a random sample of coins from his coin bank to see how many of them are older than 1982.
c: peyton randomly selects six eggs from a carton. she randomly assigns three of them to be boiled for 10 minutes and the other three are boiled for 15 minutes. after they have cooled she compares how easy they are to peel.
for which of these studies can we draw conclusions of cause and effect?
a
b
c
none of them