C line question


I know that the C line has to be something everyone can objectively agree about. Which is the C here in this hypothetical situation?

C: He came home at 7 PM.
C: He came home at 7 PM when he said he’d come home at 5 PM.
C: He came home at 7 PM when he said he’d come home at 5 PM and did not call to tell me.

All statements could be true and objectively agreed about, but each detail adds to the whole Circumstance. So, which is the C that goes in the C line?