Gretchen Offers $100 to Anyone Who Can Return Her Lost

Gretchen offers $100 to anyone who can return her lost dog,Sparky.Haley returns the dog and requests the money.Gretchen says that there is no binding contract.Which of the following is true regarding Gretchen's statement?

A) Gretchen is incorrect because there is a binding bilateral contract.
B) Gretchen is incorrect because there is a binding unilateral contract which Haley accepted by performing.
C) Gretchen is correct because there is no binding bilateral contract.
D) Gretchen is correct because there is no binding unilateral contract.
E) Gretchen is correct because Haley acted incorrectly by her manner of attempted acceptance.