As Darwin was developing his ideas about evoution, he applied ideas from many fields, including geology, economics, and biology. Why was this approach important?

Explanation:

Darwin's use of many different fields of study including geology, economics, and biology was incredibly important as it allowed him to make connections between them that ultimately led to ground breaking discovery. Such as animals that that migrated to different areas and were interconnected through their geological footprints that were left behind.

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.