[Cheap Principal] Paolo, Who Is Very Knowledgeable Regarding Computers, Agrees

[Cheap Principal] Paolo, who is very knowledgeable regarding computers, agrees to purchase computers for Joe's business. Paolo is retained for that purpose only, he is paid a set rate for the job, and Joe exercised no control over the manner in which Paolo did his work. Paolo purchased computers from AAA Computers without any mention of Joe. The computers worked well and were not defective in any way. Unfortunately, Joe did not pay AAA Computers on a timely basis. Paolo, therefore, paid AAA Computers out of his own pocket because he wanted to be able to do business with AAA Computers in the future and also because his name was on the invoice. Paolo asked Joe for reimbursement, but Joe refused. Joe claimed that if Paolo had only waited, AAA Computers might have agreed to take less.
-Which of the following is true regarding any right of reimbursement Paolo is due from Joe?

A) Paolo is not due any reimbursement because he did not get permission from Joe before paying AAA Computers.
B) Paolo is only due 50% of whatever he paid because he did not get permission from Joe before paying AAA Computers.
C) Paolo is not due any reimbursement from Joe unless he can establish that Joe signed a written contract authorizing him to personally pay debts incurred.
D) Paolo is not due any reimbursement from Joe unless Paolo can establish by a preponderance of the evidence that AAA Computers would not have agreed to take a lesser amount.
E) Paolo is entitled to reimbursement from Joe.