Where do many of the plants in the phylum polypodiophyta live?

The correct answer to this question is forests.

The correct answer is -

Forest.

Polypodiophyta is a phylum of plant kingdom that includes the ferns (some having the species such as modern ferns, primitive ferns and horsetails).

Ferns (most commonly found in rainforest) are considered to be the most primitive group of vascular plants. They were the most dominant plant group that were found in forest but  now outcompeted by the more advanced groups, which are angiosperms and gymnosperms .

Thus, many of the plants in the phylum polypodiophyta are found to live in forest.

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.