Serfs may eventually work their way to freedom (usually not), if you know the term tenant farmers, individuals who work on a property with some believe that eventually they may pay their debts off and become a freeman. An enslaved person, will never believe that they will eventually become free.
-My opinion anyway (probably wrong) but worth a try.
The answer is b. a student who passes out copies of her sacred texts in front of a police station despite knowing that she will be arrested