Why does Ponyboy say he had the knife and he killed Bob when it was Johnny?*
O Pony isn't confused. He killed Bob.
O
Ponyboy is confused, potentially due to mental illness such as PTSD (post-traumatic
stress disorder)
Ponyboy is angry and wants to take the fall so Johnny doesn't go to prison
O
Ponyboy never says he had the knife

Ponyboy is confused, potentially due to mental illness such as PTSD (post-traumatic stress disorder)

Explanation:

He wants to believe that Johnny isn´t dead.

1. ( 3rd option ) peter gets into a fight with the musician because they will not play a happy song for him.

2. ( 2nd option) petty arguments like feuds lead to pointless tragedy .

i believe the answer is perspective