Which bus connects the CPU to the memory on the motherboard?

The correct choice is the System Bus, as it serves as a communication system that transfers data between components inside a computer, particularly between the CPU and memory. The System Bus is typically composed of multiple lines that include the data bus, the address bus, and control signals which allow the CPU to retrieve data and instructions from memory. This enables efficient data communication and is essential for the functioning of the computer system as a whole.

In this context, while the Data Bus specifically carries the actual data being transmitted, and the Address Bus carries the locations of data in memory, it is the System Bus that encompasses both to facilitate overall communication. The Expansion Bus, on the other hand, connects additional peripherals to the motherboard but is not directly involved in the core communication between the CPU and memory. Thus, the System Bus is the most accurate answer because it integrates multiple functions necessary for data transfer between the CPU and RAM.