Your computer is slow to start, and file access in Windows is slow. Which Windows feature should you use to improve performance?

System Restore reverts system files, installed applications, Windows Registry, and system settings to a previous point in time, which does not directly address slow file access due to fragmentation.

Windows Defender is an antivirus and anti-malware program that protects against malicious software but does not improve performance related to fragmented disk files.

Disk Defragmenter reorganizes fragmented data on a hard disk drive (HDD), consolidating pieces of files that are scattered across the drive into contiguous blocks. This reduces the time the read/write heads need to locate and retrieve file data, directly improving file access speed and overall system responsiveness, including startup.

Disk Format prepares a storage device for use by erasing all data and setting up a new file system, which would destroy all data and not resolve fragmentation on an existing system without a full reinstall.