In a three-pronged plug, one flat prong carries current from the supply that enters the electrical outlet, and the other returns the current to the service panel of the building. The round prong helps protect people from electrical shocks. What has a purpose similar to that of the round prong?

A a magnet
B a generator
C the plug's plastic covering
D the holes in the flat prongs

Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. which one, if either is correct? a. beryl, because low thermal conductivity results in low heat transfer. b. beryl, because low thermal conductivity results in high heat transfer. d. sapphire, because low thermal conductivity results in high heat transfer. e. neither, because low heat transfer is desirable both in summer and in winter.