Explanatory terms in a sentence are often enclosed by a. parentheses. b. hyphens. c. semicolons. d. commas.

the correct answer I believe is A. commas

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.