What three explanations does suetonius give as to why Caesar was so unprotected on the Ides of March?

Here is an extract from the text of the Life of Julius Caesar in The lives of the Caesars by Suetonius:

86 Caesar left in the minds of some of his friends the suspicion that he did not wish to live longer and had taken no precautions, because of his failing health; and that therefore he neglected the warnings which came to him from portents and from the reports of his friends. Some think that it was because he had full trust in the last decree of the senators and their oath that he dismissed even the armed bodyguard of Spanish soldiers that formerly attended him. Others, on the contrary, believe that he elected to expose himself once for all to the plots that threatened him on every hand, rather than to be always anxious and on his guard. Some, too, say that he was wont to declare that it was not so much to his own interest as to that of his country that he remain alive; he had long since had his fill of power and glory; but if aught befell him, the commonwealth would have no peace, but would be plunged in strife under much worse conditions.

87 About one thing almost all are fully agreed, that he all but desired such a death as he met; for once when he read in Xenophon [a Greek historian, philosopher and soldier] how Cyrus [the Persian emperor] in his last illness gave directions for his funeral, he expressed his Horror of such a lingering kind of end and his wish for one which was swift and sudden. And the day before his murder, in a conversation which arose at a dinner at the house of Marcus Lepidus, as to what manner of death was most to be desired, he [Ceasar] had given his preference to one which was sudden and unexpected.