A memory bus is mainly used for communication between

1processor and memory
2processor and I/O devices
3I/O devices and memory
4input device and output device

Answer:- 1

Explanation:-

Solution:

The memory bus is a type of computer bus, usually in the form of a set of wires or conductors which connects electrical components and allow transfers of data and addresses from the main memory to the central processing unit (CPU) or a memory controller.

Source : techopedia.com