I may have not explained very well, but the distinction is that a "persistent person" is more than a person who just do what should be done. A "persistent person" will try again and again where other person would have giving up. This is not present in 'c': the person just do all the possibilities. They don't try again and again where other persons have given up. They are just doing all the tasks on the list, but they will give up on a specific task as soon as any other person if there is difficulties in one task.
(edit: I should maybe not have said, in 'c' "while other models abandon", because it was misleading: my point is that these models are abandoning at the first small hurdle, or even 'forget' the task. It feels that "traditional model" should have been called "lazy model" and "persistent model" should have been called "non-as-badly-lazy model")
(edit: I should maybe not have said, in 'c' "while other models abandon", because it was misleading: my point is that these models are abandoning at the first small hurdle, or even 'forget' the task. It feels that "traditional model" should have been called "lazy model" and "persistent model" should have been called "non-as-badly-lazy model")