There are 20 staff members in a unit.① Some people have a bachelor's degree; ② The person in charge of the unit is not a bachelor's degree; ③ Some people are not a bachelor's degree. Only one of the above three judgments is true. Which of the following correctly represents the number of staff with bachelor's degrees in the unit? ['0 people have a bachelor degree.', "Only 1 person has a bachelor's degree.", '0 individuals are not bachelor degree.', "Only 1 person is not a bachelor's degree."]