What is the main idea of Jean Paul Sartre's philosophy?

1. The existence of human beings is a project that develops in a special connection with the world.
2. The reality of the world is the main focus of philosophy.
3. The existence of human beings is not something that is given, but rather something that is constructed.
4. The characteristics of Sartre's philosophy are anthropocentrism and objectivism.
a) Only statements 1 and 3 are correct.
b) Only statements 2 and 4 are correct.
c) Only statement 1 is correct.
d) Only statements 1, 2, and 3 are correct.