Why "Ο άντρας ο εαυτός του είναι υπεύθυνος" is wrong?
Ο εαυτός του=his self. I can't think of a reason as to why it's in the hints, but it's not top of the list, so it should be correct for another sentence.
Ο ίδιος ο άνθρωπος είναι υπεύθυνος Should be correct, no?
Could this relate to global warming, or paying your debts?
Well, a single man being responsible for global warming would make him a superhuman, I guess :p