Answer:
Option D i.e., Keylogger is the correct option.
Step-by-step explanation:
It is also known as the keystroke logger, which is an application used to logs or follow the keys of the struck on the users keyboard.
So, while the machine of the user acting like unsystematic manner and the user has encountered sluggishness and latency in feedback and they found txt files that seem to hold bits of some messages or interactions with colleagues online.
Then, the technician has to be execute a software that is Keylogger to detect a problem because the the following malware is the keylogger malware.