Jim wants to conduct a survey of U.S. teens aged 13 - 15 to find out what songs are their favorites. To do this, he does a random survey of 300 teens aged 12 - 15.

Which of the following correctly describes his sample?
This method of sampling is neither biased nor unbiased.
This method of sampling is unbiased.
This method of sampling can be considered both biased and unbiased.
This method of sampling is biased.