There can be many caused to the change of Earths temperature but one would be the use of fossil fuels. This is because when burned it releases Greenhouse gasses which are trapped in the atmosphere and causes heat. Which eventually leads to Global Warming. (Hopes this helps! )
4) Polaris
Stars emit light with energy generated by nuclear fusion, think of the Sun as an example. Polaris is a star, it's the brightest star in the little bear constellation, and therefore the correct answer.
