Which of the following operating systems uses the ext4 filesystem type?

The ext4 (fourth extended filesystem) is a journaling file system that is the default for most modern Linux distributions. It is the successor to ext3 and was designed to improve performance, increase storage limits, and enhance reliability. While other operating systems can read ext4 partitions with third-party software, Linux is the only operating system among the choices that uses it as a primary, native filesystem.

A. macOS: Natively uses the Apple File System (APFS) and historically used HFS+. It does not use ext4.
B. iOS: Uses the Apple File System (APFS), which is optimized for the flash/SSD storage used in Apple's mobile devices.
D. Windows: Primarily uses the New Technology File System (NTFS) and, for server editions, the Resilient File System (ReFS).

1. The Linux Kernel Archives. (2023). The ext4 Filesystem. Kernel.org. Retrieved from https://www.kernel.org/doc/html/latest/filesystems/ext4.html. In the introduction, it states, "ext4 is an advanced level of the ext3 filesystem...". The entire document details its implementation within the Linux kernel.

2. Microsoft. (2023, October 12). NTFS overview. Microsoft Learn. Retrieved from https://learn.microsoft.com/en-us/windows-server/storage/file-server/ntfs-overview. This document specifies that NTFS is the "primary file system for recent versions of Windows and Windows Server."

3. Apple Inc. (2023). Apple File System. Apple Developer Documentation. Retrieved from https://developer.apple.com/documentation/foundation/applefilesystem. This official documentation states, "Apple File System (APFS) is the default file system for iOS, iPadOS, macOS, tvOS, and watchOS."

4. Arpaci-Dusseau, R. H., & Arpaci-Dusseau, A. C. (2018). Operating Systems: Three Easy Pieces (Version 1.00). Arpaci-Dusseau Books. In Chapter 40, "File System Implementation," Section 40.2 discusses the evolution of Linux filesystems, culminating in ext3 and its successor, ext4. (Available at https://pages.cs.wisc.edu/~remzi/OSTEP/)