Equality of introduces the free rider problem.

We don’t know the parts of the story you’re talking about and don’t know what even happens in the story, so we can’t you. try being more specific when you ask for .

Im thinking a.  at the top left-hand corner

D. because a physical change doesn't involve anything that's chemically changing the substance (when you think about physical change, think about stuff like color changes that doesn't change the substances chemical makeup)