Agroup of seaside sparrows competing for food, nesting space, and mates in a salt marsh is an example of the level of environmental organization.

The answer is population.

Explanation:

This is the second level of environmental organisation, just above the individual level, which comprises every living organism by itself. The next level concerns the population of a species living in a determined area. In the passage, the example is a group of seaside sparrows.

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."