IN: Which person is they?
Amazon offers a generous credit program for college books because they want students to come back and use their credit for more purchases.
OUT: Amazon

IN: Which person is she?
Cathy let Joanna into her car, so she could take a test drive.
OUT: Joanna

IN: Which person is he?
Ryan has much less hair than Gary, so he does not go out in public without a hat.
OUT: Ryan

IN: Which person is they?
The students read the books because they were learning.
OUT:
The students