Either an groundwater source, like a well, or from a surface-water source, such as a river, lake, or reservoir.
B. Better managing our natural resources
Rapid cooling can be caused when the atmosphere has too much oxygen in it.
Westward expansion meant that the US acquired ever increasing amounts of land, and needed people, farmers, to settle there so it could maintained without a huge military presence
I think the correct answer from the choices listed above is option B. With regards to environmental changes, they may affect several populations in an ecosystem because it is where living organisms dwell and they try to adjust accordingly to these changes. Hope this answers the question.
