Which of these singular nouns has an irregular plural form?
a. foot
b. house
c. chimney
d. bear

what are the following?

there is a sequence and logical steps to give an answer of a trouble.

1) strategy is necessary to develop an project idea.

2) to study and know the environment where you are going to work ( ecosystem).

3)   the materials resources to built the ideas.

4) to give a priority order in the context that you study. in this case human needs.