What were the environmental conditions along the northwest pacific coast that allowed pacific northwest peoples to develop such large and densely populated societies?

The Pacific Northwest is an area that is particularly rich in resources and therefore, can sustain a very large population. The Pacific Northwest is very rich in water sources, as well as in timber. This allowed people to have constant drinking water and to be able to build shelter. It is also plentiful in terms of food, as it has lots of fish in the oceans and rivers, in particular salmon. All of these characteristics were crucial for the establishment of large settlements.

i beleive that d is the right answer