C.) Would be my first answer because if I'm both passionate about a topic and the trends data are showing that I can be an opportunist about it. I would be more than willing to do so. I would clearly understand the community at whole while simply just doing data test runs with marketing and other factors.
Then we have A.)..... If it were only A.) I feel that I could possibly build a following based on the same passion that I follow. Which I would be in control of moreover. If that doesn't work, I would debate about either abandoning ship or finding another twist to my passionate niche method(combine,merge with another, etc). I will already have experience with empathy understanding what the end user is expecting, as someone who understands the niche a lot clearer.
If you go with clearly B.) based on trends and statistics. You might look like a fool if you really fail at studying your target market. I feel there is a lot more homework involved since you have to actually study the behavioral patterns with your market as well. Which is a huge disadvantage as if the answer was clearly A. You will come in there live, looking like a crazy newbie if you aren't careful. So it would take you a lot longer to build a reputation, where anyone would even consider looking into whatever promotion you are pushing. Unless you had some other ulterior motive with looking weak and helpless in a niche.