Answer:
Purpose for living.
Step-by-step explanation:
The phrase "raison d’être" means the very reason or purpose of one's existence in the world. This means that it refers to the meaning behind one's existence.
In the given passage about Hans, the statement that "his life would be empty and meaningless" shows how his artwork is of extreme importance to him. Hans's expression of the value of his artwork reveals that it is, in fact, the only purpose of his existence.
Thus, the correct answer is the fourth/ last option.