Answer:
b. the interface between the hard disk and the system bus
Step-by-step explanation:
A controller, in the most basic computing terms, is a hardware chip or card that falls between two hardware components. Thus, a computer’s motherboard will always have a controller that interfaces with RAM, hard disk, DVD drives or other hardware components. Being an interface between two hardware devices facilitate incoming and outgoing commutations. Option B therefore, is the correct answer because it interfaces between the hard disk and sytem bus, which are both hardware components.