Which file system is commonly used in Linux and Android OS?

The ext4 file system, also known as fourth extended filesystem, is widely utilized in both Linux and Android operating systems due to its advanced features, stability, and performance. It is the successor to ext3 and brings enhancements such as journaling, which helps protect against data corruption, and support for larger file sizes and volumes.

In Linux environments, ext4 is the default file system for many distributions, providing a balance between performance and reliability. This makes it an ideal choice for operating systems that require robustness in handling files and directories. Similarly, Android OS, which is built on the Linux kernel, also leverages ext4, benefiting from its efficiency and speed when managing app data and system files.

The other file systems listed have specific use cases that do not align with the general usage in Linux and Android. NTFS (New Technology File System) is primarily used in Windows operating systems, ReFS (Resilient File System) is designed for Windows Server environments, and APFS (Apple File System) is specifically tailored for Apple's devices. Thus, ext4 stands out as the correct answer for both Linux and Android operating systems.