Which of the following is a biased sample of the people who shop at a shoe store?
a) Select every tenth shopper.
b) Choose the 10 most frequent shoppers.
c) Put the name of every shopper into a box and pick 10 shoppers without looking.
d) Select one shopper who enters the store every half hour until 10 shoppers have been chosen.
Please dont waste my points. Also please no links please type it for me