Which Person Is at Least Risk of Developing Dementia

Which person is at least risk of developing dementia?

A) Sara, who graduated high school and is a clerk at a gas station
B) Susan, who did not graduate from high school, but is a successful insurance salesperson.
C) Sandi, who graduated from college and is a manager at a rental car company.
D) Suri, who graduated with a Ph.D. and does research on treatments for autism.