This is the most appropriate case in which to use the word "boundary." A line that sets a limit on a map (for example, to limit the extent of a country) is called "boundary." It can also be called "border" or "frontier." Although the word "edge" is often a synonym, it cannot be used in the same way in this particular case.
This is your English Teacher, stop using this website for answers, i will email youre guardians about this, and the whole classes to re-assure they dont use this!
I would say D but that's just because I already know the definition of automation is the use of largely automatic equipment in a system of manufacturing or other production process.
