$7.$ Which of the following two can be considered valid justifications for treating memory operations as equivalent to I$/$O operations with external devices. Select both that are applicable.

a Memory can be removed and replaced, just like external devices

b Memory addressing and data movement type instructions can be used to perform I$/0$ operations.

c Both memory and $1/0$ operations are controlled by the processor over the system or processor bus.

d Memory and I$/0$ modules are accessed by the processor, making them important for the computer system