The further objects are away from each other, the smaller the gravitational force.  Planets moving apart means there will be more or less gravitational force between them?
less

Developing nations will also increase demands on natural resources as they build more factories.  If China decides to build fewer factories to produce goods, what will happen to their demand for natural resources increase or decrease?
decrease

The hotter a main sequence star is, the brighter it is.  Rachel was looking into the night sky. The darkest star is most likely: the hottest or the coldest?
the coldest