What characteristic do two tones of diffrent pitches that are an octave apart have?

The five possible reasons explaining why art may be created are

Behaviorists focus on behaviors that.. a are observable b are caused by unconscious desires and conflicts c people become consciously aware of d can be categorized into a theoretical system

Apiece of artwork, either 2-d or 3-d, which is composed by an artist using the elements and principles of art is called a