The boundary where two or more air masses meet is called

Since the question is asking for a nonscientific question you want to rule out answers that would be reasonable to ask that has something to do about the birds.

Think of the questions as a experiment. D. Would the birds still visit if the seed in the feeders were changed. That would be a very good scientific explanation. So D. is wrong.

C.At what time of day do the most birds visit the feeders. That would be a fun scientific experiment wouldn't it? That rules C out.

Now you have A. and B left. B. Does having a birdbath present affect the feeding habits of the birds? That would be another good experiment.  Your answer is A. What color are the beaks of the small birds that visit the feeders?

I hope that helps! If it does please mark me brainiest, if it doesn't please don't.