The power delivered is equal to the product between the voltage V and the current I:

This power is delivered for a total time of

, so the total energy delivered to the battery is
The best and most correct answer among the choices provided by the question is the third choice. What he observed on the waves is the constructive interference. I hope my answer has come to your help. God bless and have a nice day ahead!
Answer:
I didn't understand your language I hope you'll write in English language next time