Activation Lock is a feature that prevents anyone from erasing or activating an iOS device without the owner's Apple ID and password. If a corporate-owned iOS device is linked to an employee's Apple ID, it will have an Activation Lock issue when the employee leaves the company or forgets their Apple ID credentials.
Reference: CompTIA A+ Core 2 Exam Objectives, Section 4.1

A keylogger is a type of malware that captures user input, such as keystrokes, mouse clicks, and clipboard data, and sends it to a malicious actor. Keyloggers can be used to steal passwords, credit card numbers, personal information, and other sensitive data.
Reference: CompTIA A+ Core 2 Exam Objectives, Section 5.1

Disk Defragment is a tool that can be used to improve the performance of a hard disk drive (HDD). HDDs store data in sectors and clusters on spinning platters. Over time, as data is written, deleted, and moved, the data may become fragmented, meaning that it is spread across different locations on the disk. This causes the HDD to take longer to access and load data, resulting in slower performance. Disk Defragment consolidates the fragmented data and rearranges it in a contiguous manner, which reduces the seek time and increases the speed of the HDD. Disk Management, Disk Cleanup, and Device Manager are not tools that can alleviate the issue of slow HDD performance.

Resource Monitor will help a technician identify the issue when a user reports a computer is running slow1

This is because a PIN is a fast and secure method of logging in to laptops, and it is more secure than a password because it is not susceptible to keyloggers.