(urgent) alejandro wants to determine the average shoe size of all of the male students in his school. which sample is likely to yield the most biased results?

every tenth boy on the school’s phone list
every member of the boys’ basketball team
every boy in a randomly selected ninth-, tenth-, eleventh-, and twelfth-grade gym class
every fifth boy who walks through the front doors of the school in the morning

Well, I think that the answer is :

Every member of the boy's basketball team.

Why?

Because people on the basketball team are usually extremely tall, or are much taller than their average classmates, and taller people have bigger feet, making this sample very biased.

It would not be every 10th boy on the school's phone list because this would be completely random and unbiased.

It would not be every boy in a randomly selected ninth-tenth-eleventh-twelfth grade gym class because, once again, this is super random. So, this is unbiased.

It would not be every fifth boy who walks through the front doors of the school in the morning, because this is totally random, guys who walk into the school are not likely to have big feet, but are not likely to have small feet either. So, this is unbiased.

So, once again, your answer is : 

Every member of the boy's basketball team.

~Hope I helped!~

1. 5/82.95% is better than 7/8