To create a bootable macOS installer that includes macOS Recovery on an external storage device, you need to use the Mac OS Extended format, also known as HFS+. This is because the createinstallmedia command, which is used to create the bootable installer, requires the volume to be formatted as Mac OS Extended. APFS (Apple File System) is not supported by createinstallmedia, and neither are the encrypted versions of APFS or Mac OS Extended. Therefore, the correct answer is D. Mac OS Extended.  References :  Create a bootable installer for macOS ,  How to create a bootable USB macOS installer ,  How to format the startup drive for a Mac