Why should a visual inspection be the very first step of a diagnosis, before reaching for an instrument?

Select one answer.

• Because it is the fastest, cheapest, and safest test there is — it needs no power or setup beyond light and often finds a visible fault in seconds that blind probing would take an hour to isolate.
• Because looking at a board for long enough physically repairs most of its faults on its own, so that in many cases no measurement or soldering is ever actually needed.
• Because the rules of repair forbid ever using a meter until the board has first been stared at for a fixed minimum number of minutes, regardless of what is found.
• Because a visual inspection is the slowest and most expensive test available, and doing the hardest test first is always the correct way to begin any diagnosis.