Answer:
Ea public address glven via the intercom system of a large buildingxplanation:
Your allowed to switch lanes as long as the road is clear and you use signals.
Carbon is not used as semiconductor it has 4 valence electrons in it valence shell but the energy gap is very small it will conduct electricity even at room temperature ,the size of carbon is very small .
I believe the answer is D: brazing
Hope this helps you have a good night