Which of the following samples would constitute a biased sample?

Seventh grade girls were randomly surveyed to determine what theme the whole school would prefer for the dance.
A tele-market research company randomly called and surveyed one thousand men and women over the age of 65 to determine which insurance companies were preferred in retirement.
Kids at a large preschool were randomly surveyed to determine the color most preschoolers like best at that school.
Two thousand people were randomly surveyed about their favorite candy in four different cities in Arizona to determine Arizona’s favorite candy.