There seems to be 2 schools of thought here:
1. Try it first, and if you don't succeed, get someone else's solution.
2. Try and try again (without looking at someone else's solutions) until YOU solve it.
I reckon the second one is better - even if it takes longer to solve.
A student will learn more by struggling with one hard problem until he or she gets it out, than by doing 1000 problems by rote or by reading someone else's solutions.
So I still reckon Affinity's option 4 is best.
Here's how Andrew Wiles describes how he does maths:
Perhaps I could best describe my experience of doing mathematics in terms of entering a dark mansion. One goes into the first room, and it's dark, completely dark. One stumbles around bumping into the furniture, and gradually, you learn where each piece of furniture is, and finally, after six months or so, you find the light switch. You turn it on, and suddenly, it's all illuminated. You can see exactly where you were.
Notice how there's no mention of looking up solutions written by the fairies!