That could be letter B: flowchart. Flowchart diagrams
can be used to easily service an electronic circuit board with ICs because they
let you see the flow of the current as you could imagine it. You can use
different shapes to further your explanation and illustration on how the
electricity flows from a source, to its medium to the switches. You could also
decide on flowcharts and be able to see where that decision leads you and you
could also try to learn different decision methods which is basically
illustrated on the chart.
