When does upward growth of cities typically occur?

a.

when water resources are limited

b.

when waste production is a problem

c.

when available land is limited

d.

when population exceeds 100,000

The difference(s) between the grand canyon and valles marineris is/are: (a) the grand canyon was formed by water, but valles marineris was not. (a) valles marineris is much longer than the grand canyon. (c) valles marineris is much wider than the grand canyon. (d) valles marineris has large volcanoes near it. all of the above

How are farmers that use no plow farming methods able to improve air quality for the people around the fram

Gemstones are commonly found in pegmatites, which are igneous rocks that are a. exceptionally mafic b. exceptionally coarse grained c. exceptionally fine grained d. extrusive, forming from lava