Helen's cat Fluffy has run away, and she places reward posters throughout her neighborhood. Mark sees one of the reward posters and spends the next six hours searching for Fluffy. While Mark is searching the neighborhood, Fluffy gets hungry and comes home.
a) Mark is entitled to the reward because he fulfilled the conditions of the offer
b) Mark is not entitled to the reward because Fluffy returned home on her own
c) Helen is not obligated to pay the reward because Fluffy returned home on her own
d) Mark is entitled to half of the reward because he put in effort
