" In an action for breach of contract brought against Ohner by the proper party, will Ohner be successful in asserting as a defense his inability to obtain a loan?
Yes, because obtaining a loan was a condition precedent to the existence of an enforceable contract. 
Yes, because the agreement about obtaining a loan is a modification of a construction contract and is not required to be in writing. 
No, because the agreement about obtaining a loan contradicts the express and implied terms of the writing. 
No, because Ohner is estopped to deny the validity of the written agreement