A. It will melt; B and C don't make sense, for obvious reasons. And when something is heated up, its particles move faster, not slower.
B. I think thats right :/
The correct answer is option D
Ali is using a specialized headphone that cancels the extra noise in the atmosphere.
Megan is using a transmitter to convert electrical signals into radio waves.
Kristoff is using a microphone to convert sound waves into the electrical signals.
Jenna is using the radio to convert radio waves into sound waves.
A control is a experimental variable that is kept constant or unchanged during an experiment. During a controlled experiment, the controlled variables are held constant to minimize or stabilize their effects on the subject, its unchanging state allows the relationship between the other variables being tested to be better understood.