18. Is the farmer obligated to make the $4,000 payment?

A is correct. Under the doctrine of constructive conditions, a party's contractual obligation is conditioned upon the other party's substantial performance. However, where one party's performance requires a period of time (such as the painter's obligation to paint the barns), that performance is due before the other party is obligated to perform unless the contract specifies otherwise. In this case, the farmer-painter contract not only failed to provide for progress payments, but it expressly provided for payment only «upon the painter's completion of the work on all three barns.» Thus the farmer was not obligated to pay any portion of the contract price until the painter had substantially completed painting the three barns.

B is incorrect. The painter had no right to payment after completing the first barn.

C is incorrect. The contract is not divisible because it does not call for payment of $2,000 after each of the barns is completed.

D is incorrect. Painting two of the three barns does not appear to be substantial performance. Even if it were, the express terms of the contract may be construed as expressly conditioning the painter's right to payment upon completing all three barns.