Pls answer quickly and without a link Select all the correct answers.
Select all studies or experiments in which the results might have been skewed by a bias or improper sampling.

a study on fish length correlated to size of living environment, where 30% of the sample had a z-score greater than 2
a survey of science fiction film fans found approximately 95% of fans had a z-score between -2 and 2
a statewide study on highway maintenance that resulted in a large standard deviation around the mean
a study of the freezing temperature of a new compound found a small standard deviation around the mean
a survey of a high school's graduating class of 428 students conducted on 100 randomly selected seniors
a national survey conducted by polling 100 users at a popular website