Why are you worried about rats but not about mice?
a. Because mice don't attack humans but rats do.
b. Because rats attack humans.
As far as I know, rats rarely attack humans, but they might indeed do so. Would sentences (a) and (b) be acceptable in this conversation? They seem to be making a very general statement, but actually, in the conversation they are not supposed to do so.
I think they work in this converstaion. Here they do not mean all rats attack humans, but simply that a rat might attack a human being.
What is your verdict?
They're both inaccurate, but in conversation people could use them.