Select the correct answer. Which theme does Leo Tolstoy explore in this excerpt from The Death of Ivan Ilyich?

"Then what does it mean? Why? It can't be that life is so senseless and horrible. But if it really has been so horrible and senseless, why must I die and die in agony? There is something wrong!

"Maybe I did not live as I ought to have done," it suddenly occurred to him. "But how could that be, when I did everything properly?" he replied, and immediately dismissed from his mind this, the sole solution of all the riddles of life and death, as something quite impossible.

A.
Humans are shortsighted and inconsiderate toward others.
B.
Love is unpredictable and can be used to fulfill selfish needs.
C.
Human mortality is inevitable, and it is important to live an authentic life.
D.
Materialistic minded people cannot change no matter how difficult life becomes.