Which of the Following Would Best Satisfy the Requirements for a Good

Which of the following would best satisfy the requirements for a good legal offer?

A) "I'll pay you at least $300 for your horse, Blackie, and even more if the horse is lucky."
B) "I'll drive you to Seattle on Saturday."
C) "The purchaser will pay $1000 for one of the seller's laser printers, the exact model to be determined at a later date."
D) "I'll give you $1 for your new green bike."
E) On a flyer placed on your windshield) :"We have the best offer in town! A mint 1956 Chevrolet for $20,000."