After going through all the responses and queries by Aditi, first, I would like to say that she, as well as all candidates if found in the same kind of situation, must not feel like they can be rejected because of being vegetarian or non-vegetarian. There can be more reasons for rejection and selection that play an important role in this process, but yes, this can be one of the reasons too.
Secondly, if an interviewer rejects any candidate because he/she is a vegetarian, it will not be acceptable and is a very unprofessional act.
These kinds of questions are generally asked by interviewers/employers from retail/FMCG sectors, so there is nothing strange about it. I also experienced this a few years back. By asking this, the interviewer actually wants to know about the decision-making skills of a candidate – what one would do in a different situation or when faced with something not acceptable to them. "It's life, and there are many stages where we have to do things we never thought of or liked to do, which is a fact."
Moreover, questions for judging the decision-making skills of a candidate vary with work functions/categories, but this is a very common question that can be asked of any candidate to understand their attitude, approach towards life, and whether they can accept challenging conditions or not.
Perhaps, few people won't accept or understand it, but it is a truth asked by interviewers. Discrimination certainly is not acceptable. Regarding MNCs, you should not worry because there is a big difference between interview questions and living (working) a corporate professional life in reality. You are totally free to choose what to eat while working.
@To All: As Aditi was assuming what could be the reasons for her rejection (if rejected), which is common for newcomers, I suggest to all candidates not to worry and to be confident and wise with your answers as this is a crucial stage for you.
@Aditi Lastly, as you have been selected and offered a good package initially, this can certainly be helpful in job searching, but there is something I would like to highlight by referring to the same question asked by the INTERVIEWER.
You are a girl, and your parents' concern in this regard is understandable and acceptable, but what will you do if you get a very good opportunity to work outside your city/country, which could be a golden opportunity for your career and professional life? At this early stage, you might not be able to go, and your parents might not allow it, but in the future, would you like to work outside your town?
Best of luck in making your decision.