Is the verb in the sentence in the active voice or the passive voice?

the phone bill was paid before its due date.

a.
passive voice

b.
active voice

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.

it was a big part of the story, making a lot of plot points happen?