Which of the following would best satisfy the requirements for a good legal offer? a$"$I$\text{'}$ll drive you to Seattle on Saturday." bOn a flyer $($placed on your windshield$)$: $"$We have the best offer in town! A mint $1956$ Chevrolet for $$20000."$ c$"$I$\text{'}$ll give you $$1$ for your new green bike." d$"$I$\text{'}$ll pay you at least $$300$ for your horse, Blackie, and even more if the horse is lucky." e$"$The purchaser will pay $$10$ for one of the seller's laser printers, the exact model to be determined at a later date."