What kind of delivery uses a clocking circuit to control the timing of communications between two WAN devices such as routers?

The kind of delivery that uses a clocking circuit to control the timing of communications between two WAN devices, such as routers, is known as synchronous transmission. In synchronous transmission, data is sent in a continuous stream, synchronized with a clock signal, ensuring that both sender and receiver are aligned in timing. This allows for efficient and accurate data transfer, minimizing the risk of errors that can occur with asynchronous methods, where data is sent without a shared clock signal.