The correct answer is D) Aluminum and copper alloys are prohibited from being in valve parts in contact with the cargo. This is correct because the carriage of anhydrous ammonia is governed by regulations that prohibit the use of aluminum and copper alloys in valve parts that come into contact with the cargo. Ammonia is highly corrosive and can react with these materials, which could lead to equipment failure and potential hazards. The other answer choices are incorrect because they do not accurately reflect the specific regulatory requirements for the carriage of anhydrous ammonia on a tankship.