Final answer:
The most inappropriate comment for a social media post within a professional context is option c as it involves bad mouthing a former employer, which can lead to negative professional repercussions. Option c is the correct answer.
Step-by-step explanation:
In the context of professional etiquette on social media, certain comments can be detrimental to one's career or future job prospects. Upon reviewing the provided examples, one can discern that the most inappropriate comment for a social media post would be related to bad mouthing a previous or current employer.
The first two examples (a and b) involve networking and seeking career opportunities, which are considered positive uses of social media. Example d demonstrates gratitude toward a service received, which is also professional and appropriate.
However, option c, "Quit my job today! No more being exploited and unappreciated!" directly involves bad mouthing a former employer, which can lead to a negative perception of the poster's professionalism and could potentially damage future employment opportunities. This kind of behavior disregards the importance of maintaining a respectful professional profile online as it may be seen by potential employers or colleagues.