Over time, abstract art has become a recognized and valued part of art history. This is an example of.

Deterioration of artistic standards.

Changes in artistic style over time.

Different interpretation of what makes good art. (MY ANSWER)

The way fads come and go.

Your answer, "Different interpretation of what makes good art," is correct. Over time, art movements and styles change as a result of varying interpretations of what constitutes meaningful and valuable artwork. Abstract art, like any other artistic style, has faced its share of criticism and skepticism. However, as time passed, society and art institutions began to appreciate its unique aesthetic qualities and the ways it challenged traditional artistic norms. This appreciation ultimately led to the recognition and value attributed to abstract art in the larger context of art history.

I agree.