What do the piano players and the man pacing the second floor symbolize?

Mental instability

Explanation:

playing a piano helps to reduce the Mental health cases like anxiety and depression. studies have shown this to be true, it can also help your over all health situation because Music soothes the soul of someone who is engrossed in it passionately. a piano player symbolizes someone who might be anxious or depressed which is categorized as mental instability

Pacing the floor is a symbol that one is anxious ( anxiety ) of something that is going to happen or has just happened in a situation. and Anxiety is part of the Mental health of an individual hence the man pacing the floor at a particular point in time is said to be having Mental instability due to his anxious nature at the time.

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.

i think that it is letter d.