"every student in this room is affected by the pollutants hidden in these walls" stated in a speech introduction is

I believe the answer is: a statement of significance

In speech, a statement of significance refers to directly conveying the important part of the message at the beginning of the speech. This technique is used by speakers to obtain fast initial attention from the audiences. This is commonly done in a short duration speech

well it depends i think people around the world are coming around to gay marriage. but if you are talking abortion then wow, so much to talk about. such as men thinking they have the right to choose if women can, the fact there are health concerns if the women can't get one, and many more arguments to discuss. so i would definitely say abortion would be a much more interesting topic.