We don’t specifically cover float switches anywhere, because they’re extremely simple devices — just a floater that activates a switch once the water level pushes it high enough.
This video shows it in action pretty well:
Q8. If you had read that statement without any other context, then yes, you would be correct in thinking that a stuck timer contact is a potential cause of the problem.
However, that statement in the explanation for Q8 shouldn’t be taken in isolation. It’s part of the logical flow of the question, which previously stated that you had confirmed that line was not reaching the inlet valve.
Knowing this, and knowing the rule of thumb that there’s usually only one problem at a time, your next step is to determine what could interrupt line to the inlet valve. Since the other components are receiving line, you can safely deduce that the only thing it could be is a broken wire.