Which example would be likely to give a valid conclusion?

Five people are randomly sampled and asked about their eye color.
Sarah asks the girls on her soccer team what their favorite sport is.
In a data set of 20 data points, the mean and median are different and there is no mode.
Ten students from each class are randomly sampled to find the favorite subject at school.

Question

Which example would be likely to give a valid conclusion?

Five people are randomly sampled and asked about their eye color.
Sarah asks the girls on her soccer team what their favorite sport is.
In a data set of 20 data points, the mean and median are different and there is no mode.
Ten students from each class are randomly sampled to find the favorite subject at school.

anonymous · Answer

Hint: Which of the choices seems the most definite to you? (By that I mean, which one seems least likely to depend upon chance, that chance of which is involved with variety?)
I hope that helps! (^_^)

triciaal · Answer

Another hint: which option will give answers that no one can change ?