Joe Find a Dog Wandering in His Yard and He

Joe find a dog wandering in his yard and he let it into the house. A day later he sees an advert on a tree stating that the owner of the dog will pay $100 to anyone who finds and returns the dog to the local SPCA office. Joe takes the dog to the local SPCS office. Which of the following is true?

A) The kind of advert that is placed on the tree cannot give rise to a contract.
B) Joe will be entitled to the reward because his performance of the obligation, in response to the offer, is all that is needed in a unilateral contract.
C) The advert on the tree is an invitation to do business and cannot give rise to a contract.
D) When Joe takes the dog to the SPCA, he makes the offer and if the SPCA accepts the offer, they are obliged to pay him.
E) Joe did not communicate his acceptance of the offer to Mary and so no contract arose.