A two-piece gravity flush water closet has the following parts in the tank.

• A. Fill valve and overflow tube
• B. Flush valve and overflow tube
• C. Ball cock and flush valve
• D. Ball cock and fill valve

Answer: (C)

In a gravity-flush two-piece toilet, the tank contains the two essential controls: the fill valve (often called a ball cock) that lets water into the tank, and the flush valve that releases water from the tank into the bowl during a flush. Those two parts handle the basic operation of filling and flushing. The overflow tube is a safety feature that works with the fill valve to prevent flooding, but it’s not considered one of the two main tank controls. Since ball cock and fill valve refer to the same device, the two primary tank components are the fill valve and the flush valve.