The themes are grief, negativity, and depression. You can see this through the mood of the protagonist and the overall mood of the story.
This is one of the main axes of existentialist philosophy. Camus puts emphasis on how nothing intrinsically matters. We are the only ones that can give meaning to the world and thus the world is just a tool for us and our consciousness, we are completely alienated from it on a basic level. The concepts of freedom and the crowd are not mentioned and the concept of philosophy as a way of life is too vague to capture this. The correct answer is c.
