Darryl,a Non-Swimmer,fell Off a Boat into the Lake

Darryl,a non-swimmer,fell off a boat into the lake."Help!" he cried."$100 to the person who saves me!" Frances then jumped in and held Darryl's head above water until the boat's dinghy could reach them.

A) Darryl must pay Frances the reward since,by her action,she accepted his offer and gave consideration for his promise.
B) Since Frances did not accept his offer,although what she did would have been consideration if there had been a contract,the offer is revocable and he need not pay her $100.
C) If Frances had been under a legal duty to save Darryl,even if there was a contract that he should pay her $100 for the rescue,Darryl will not have to pay her.
D) a and c.
E) b and c.