It is called the compound microscope.
From Top to bottom: C, B, D, A. That's the correct matchups (:
Rainstorms provide natural moisture to the environment. Receiving rain will keep plant life healthy, give animals a natural reservoir to drink from, as well as keeping the life in the river healthy. Though a flash flood may cause damage to buildings and habitats at first, buildings can be fixed and over time, wild flora and fauna will return to the area, often more plentiful, is there is a good amount of moisture <span />
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.