Answer: Keyboard hardware & the operating system
Explanation:Keystroke loggers is also referred as the monitoring system which is a for the inspection of the every key pressed on an operating system. This technology monitors the activities of keypad devices such as smart phones etc. It is also used for the surveillance of the unauthorized activities that are done by the hackers or criminals.
Thus the correct option is keyboard hardware and the operating system is the location of the placement of the key loggers.
