The best and most correct answer among the choices provided by the question is the second choice. The things that we would need are: <span>hydrogen atoms, helium atoms, heat, pressure, and energy. </span>I hope my answer has come to your help. God bless and have a nice day ahead!
<span>Studying the changes in densities of pocket gophers when large herbivores such as elk are excluded from mountain forests would be an example of studying ecology at the community level.
A community refers to a group of organisms of various species that live in the same location and interact with each other. So, if this scientist is observing gophers and elks, they are looking at the level of communities, not anything more or less.
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