I believe the correct answer is Sarah always feels hungry shortly after she leaves work—right in time for dinner.
The classical conditioning (also known as Pavlovian or respondent conditioning) is a learning procedure which creates a certain habit which includes biologically potent stimulus (e.g. food) that is paired with a previously neutral stimulus (e.g. a bell). In this case, due to her working hours, Sarah starts to feel hunger just after she finish her work (her bell), which was her previously neutral stimulus, now potent stimulus.