Which bus is bidirectional?

In computer architecture, buses are pathways that transfer data between components. There are three main types of buses:

• Address bus: This bus carries memory addresses from the CPU to other components (like RAM or I/O devices). It is unidirectional because addresses only flow from the CPU to specify a location.
• Data bus: This bus carries the actual data being transferred between the CPU, memory, and I/O devices. Data can be read from memory/I/O into the CPU, or written from the CPU to memory/I/O. This two-way flow makes the data bus bidirectional.
• Control bus: This bus carries control signals (e.g., read/write signals, clock signals, interrupt requests) that manage the flow of information. Some control signals go from the CPU to other components, while others (like interrupt requests or status signals) go from components back to the CPU. Therefore, the control bus is also bidirectional.
• Uni-bus: This is not a standard term for a type of bus in general computer architecture.

Both the data bus and the control bus are bidirectional. However, in many contexts, the data bus is highlighted as the primary example of a bidirectional bus because it directly handles the two-way transfer of data content.

The final answer is $\text{B}$