One of the Most Significant Results of the Artistic Experimentation

One of the most significant results of the artistic experimentation of the 1920s and 1930s was that

A) artists learned to adhere to accepted public definitions of reality.
B) photography was no longer considered a legitimate art form.
C) generally accepted standards that distinguished between "good" and "bad" art disappeared.
D) impressionism was recognized as the single best art form.
E) a set of criteria was established that allowed art students to distinguish between "good" and "bad" art.