As the questions says, when do you stop? your point of no return?
Are you talking about stopping gambling in total or briefly then play again.
Yes, there's no mistake, if you talk about stopping temporarily and continue tomorrow.
Choice:
c. or you are a superstitions gambler, when you have signs like losing 3 straight in a row, then you quit because you know that you're having a bad luck
Yes, if you talk about stopping gambling in total, my choice.
a. at least double your money, then stop
The two points I consider for the point of stopping gambling, as I said above.