When you say "in the lay meaning", I tend to understand 'b', but then you say "they're told to complete the task, and they keep going until they have", which correspond more to 'c'.
To illustrate better the difference: you can have a loop that try different inputs and stop when the output for the tried input is lower than a given threshold. But then, you can also have the same loop that will try all the input, and then select the one that returned the lowest value. The problem is that a lay person will not call the second algorithm "persistent". It is just a normal algorithm that does the full exploration.
A second example is when a software tries to connect somewhere and does a retry with exponential backoff. A lay person will not call it "persistent".
It looks like that "normal model" are like "no-retry code": they go in one direction, but drops some of the paths and possibilities along the way at the first hurdle. But a "non-persistent" human will not behave this way. I'm pretty sure that if you try to access a website and it says "timed-out", you just try to refresh the page, and you will not consider yourself as "persistent", even less "highly persistent".
To illustrate better the difference: you can have a loop that try different inputs and stop when the output for the tried input is lower than a given threshold. But then, you can also have the same loop that will try all the input, and then select the one that returned the lowest value. The problem is that a lay person will not call the second algorithm "persistent". It is just a normal algorithm that does the full exploration.
A second example is when a software tries to connect somewhere and does a retry with exponential backoff. A lay person will not call it "persistent".
It looks like that "normal model" are like "no-retry code": they go in one direction, but drops some of the paths and possibilities along the way at the first hurdle. But a "non-persistent" human will not behave this way. I'm pretty sure that if you try to access a website and it says "timed-out", you just try to refresh the page, and you will not consider yourself as "persistent", even less "highly persistent".