Even though it's been a while since you asked the question, I'd like to add that "feel" can have either refer to a physical feeling (when someone is touched), emotional feeling (when someone is upset, happy, etc.), or beliefs. In this case, Alison's beliefs were so strong, she /felt/ compelled to speak.

Thanks all for answering me. Your responses are clear and helpful.

Alison usually did not like to express her opinions on various matters because they did not interest her that much. But on this particular issue, she had a very DEFINITE OPINION, and she wanted everyone to know what it was.

It means to have a clear and passionately held opinion. In this case, the opinion or point of view is felt so intensely that the person felt she must express it. Take care Naga