What do you think is the biggest effect of animal product consumption? → This phrasing ensures the participant is giving their own opinion, and may even yield some surprising responses that enrich your analysis.
After conducting your interviews and transcribing your data, you can then conduct thematic analysis, coding responses into different categories. Since you began your research with several theories about campus veganism that you found equally compelling, you would use the inductive approach.
Once you’ve identified themes and patterns from your data, you can draw inferences and conclusions. Your results section usually addresses each theme or pattern you found, describing each in turn, as well as how often you came across them in your analysis. Feel free to include lots of (properly anonymized) examples from the data as evidence, too.