A vessel puts into the port of Kobe，Japan to discharge cargo. While awaiting completion of the cargo operation，the vessel contracts with a local shipyard to have the hull chipped，scaled，and painted. How is the cost of this maintenance handled with the Collector of Customs?（）

A.A declaration is required and duty is involved on the total cost
B.No declaration is required since this is considered routine maintenance
C.A declaration is made and duty is charged on the materials only
D.A declaration is made，but duty is charged on the labor only