What does it mean to see a board as a signal chain?

Select one answer.

• To see it as an ordered series of stages a signal passes through from input to output, each shaping the signal, so a fault has a place on that path — the stage where a good signal becomes a bad or absent one.
• To see it as a completely random heap of components with no order and no direction at all, so a signal fault could be absolutely anywhere on the board and there is simply no way to follow the signal from one point to the next toward the fault at all.
• To see it purely as a set of power rails, since a board is nothing more than its supplies and a signal chain is just another name for the power distribution tree that feeds the components.
• To see it as a single indivisible block that either works or does not, so that a signal fault can never be localised to any particular part of the board and the whole board must be replaced.