I followed his instructions. ( simple future)

your answer is c) experiments with water vapor showed that elements combine in specific proportions.

what lesson are you referencing?

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.

xd

explanation: