Final answer:
Okonkwo hung himself because he realized that the old ways were gone and no one followed his lead against the intruders. The answer is option 3.
Step-by-step explanation:
Okonkwo hung himself because he realized that the old ways were gone since no one followed his lead and rose up against the intruders. He felt that his life and efforts were in vain, and he couldn't bear to live in a world where his values and traditions were disregarded. This realization, coupled with his son's rejection of him and the lack of recognition from his community, led him to take his own life.
Hence, the answer is option 3.