Which of the Following Persons Is Considered Part of the Labor

Which of the following persons is considered part of the labor force?

A) Joe, a senior in high school who works part-time on weekends at the ice cream shop
B) Mary, who works as a librarian in prison because she poisoned her cheating boyfriend
C) Jamal, who just graduated from college and is backpacking in Europe for six months
D) Tessa, an 8-year-old who sells lemonade on the sidewalk for 50 cents a glass