X Contracted with Z

Multiple Choice

X contracted with Z. X promised to pay $500 and Z promised to build a cabinet to hold X's fine china. The essential terms included the type and quality of the wood, the dimensions, and the date of completion-February 13. The work went more easily than expected and Z said to X, "If you pay me another $85, I will have this finished and be out of here by February 10." X agreed. If the cabinet was done to specifications by the 10th, but X refused to pay anything, Z would be entitled in law to

A) nothing.
B) $500.
C) $585.
D) only $85.
E) a "fair price."