The correct answer is A) Chain. When passing a stopper on a wire rope, the stopper should be made of chain. Chain is preferred over other materials like manila, nylon, or wire because it provides a secure, non-slip grip on the wire rope. The rigid, durable construction of chain ensures it will not damage or deform the wire rope as other softer materials might. This is in accordance with standard maritime practices and Coast Guard regulations for the safe handling of wire ropes. The other options would not be suitable choices - manila and nylon are too soft and prone to slipping, while a wire stopper could potentially damage the wire rope.