These operating systems were referred to as command-based. a. android and ms-dos b. ios and windows c. linux and unix d. ms-dos and unix

D.MS-DOS and UNIX

Explanation:

The oldest versions of Windows Operating Systems used MS-DOS. MS-DOS was purely command-line based OS. MS-DOS did not have GUI and users were required to learn command lines to help them navigate through, open, and manipulate files. MS-DOS is no longer used. UNIX was also a command-line based operating system when it was initially built in the 1960s. It still is but it supports both GUI and CLI. Unix, in my opinion, is hands down the best and most powerful CLI based OS to have ever been built.