Final answer:
The programming language popular during the MS-DOS era and known for its secure use of third-party code was C. It set standards for coding and continues to be influential.
Step-by-step explanation:
The programming language of the third generation commonly learned by students during the era when MS-DOS was widely used is C. It continues to be a secure programming language to this day, particularly for using third-party code, and it provides a standard for coding that integrates well with other programming languages. Early operating systems were proprietary before UNIX initiated a shift to more openness, yet eventually became commercialized.
In the context of the history of operating systems, we can see that while early systems had proprietary control, such as IBM, DEC or Hewlett Packard for mainframes, and Microsoft with DOS for personal computers, UNIX was initially more open before it became commercialized. This shift to commercialization is evidenced by AT&T's sale of its UNIX system rights to Novell, and then to SCO, leading to a range of proprietary UNIX versions like IBM's AIX, Microsoft's Xenix, Sun Microsystems' Solaris, and SGI's IRIX.
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