A teacher samples the students in 8th grade to decide what the 8th-grade math classes need to review for their final exam. Which
sample produces biased results? a The teacher assigns all 8th-grade students a number and then uses a random number generator to select 30 students.
b The teacher selects every third 8th-grade student who enters school one morning.
c The teacher puts each 8th-grade student's name on a popsicle stick, places the popsicle stick in a bucket, and then randomly selects 30 students.
d The teacher picks 30 8th grade students in the math club.
