What is a caldera? A: an island formed by hot magma erupting under water and emerging from below the surface of the water

B: a "recycling center" of the Earth where a dense tectonic plate slides underneath a less dense plate

C: a long, thin, deep valley formed at a divergent plate boundary

D: a deep hole in the ground formed from the fall of a volcanic mountain

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

the "power" of a lens is its resolution power, or its ability to distinguish between to closely located points. with the low power lens, it is likely you will see the rough form of the hay and maybe some movement of dots around the hay. however, when observed with the high power lens, the detailed features of the hay become visible and the microbes being grown are more clearly visible.

i hope this you