Following World War I, western art generally became

A. more popular with the common people.
B. more realistic.
C. more abstract.
D. more romantic.

C

Explanation:

Because of the trauma from the war, afterwards, art drastically changed to incorporate much more abstraction. In fact, it became a surreal form of art, even before the Surrealism Era began.

Artists felt the general disgust from the public towards the way world leaders handled the war, and they portrayed that in their artwork through nightmarish, chopped-up visions in paintings to less extravagant writing styles in literature.

Thus, the answer is C.

Hope this helps!

C. more abstract.