Which type of art has no visible subject?

In this unit, it is mentioned that in order to enter into the field of photography, most jobs require at least a high school degree. since there is a possibility you can attain one of these jobs with just finishing high school, why do some people get an associates or bachelor’s degree?

Which principle of design is in primary use in this sculpture?

What is the main element that sets western art criticism apart from that of the rest of the world