Answer:
D. The average value of the voltage
Step-by-step explanation:
Alternating current (AC) is a type of electrical current, in which the direction of electron flow comes and goes at regular intervals or in cycles. The current flowing through the power lines and the electricity normally available in the houses derived from the wall sockets is alternating current.
In the United States of America you can use your electrical devices, provided that your country's voltage is 110V and 127V (as well as in the US, Canada and most of the countries of South America). Electronics manufacturers take into account differences of 5%. Therefore, it considers an average value of 120 V.