Answer:
When there are two or more electrical devices in a circuit with an energy source, there are a couple of basic ways by which we connect them. They can either be connected in series or parallel
Sound needs medium to travel and it can not travel without medium
so sound wave is a travelling wave
now we also know that sound wave propagate in form of rarefaction and compression.
So all medium particles travel in the direction of wave only
so it is a longitudinal wave also
so correct answer will be
<em>mechanical longitudinal </em>
The sun is a clear example of objects releasing radiation in nature
Should be an air tight seal