Which of these experiments sounds the most like it would be analyzed with a Related-Samples t-test?

Group of answer choices

A study that compares the average GPA of Chaffey students to the average GPA of Mt. Sac students

A study that compares males vs females on their average level of empathy while viewing a video of a child getting bullied

A study that compares high school graduates vs college graduates on their average incomes at age 50

A study that compares the obedience levels of dogs before and after six weeks of obedience training