Abe, a homeowner who owns a pile of shingles that need to be installed on his roof, sends Bill a letter offering to pay him $4,000 to install the shingles on his (Abe's) house. Bill sends a letter back to Abe that says, "I accept your offer, but must be paid $4,500 to install the shingles on your roof." As of the moment Abe receives the letter from Bill, which of the following is true? Group of answer choices Abe and Bill have no contract. Bill's acceptance letter was effective as of the moment he mailed it. Abe is contractually bound by the terms of Bill's acceptance. The UCC will require Abe to pay Bill a reasonable amount for his (Bill's) labor