All you seem to be interested in is posting your homework problems and expecting us to solve them for you.
Doesn't work that way. You need to show YOUR best attempt to solve YOUR homework. We will then help you see where you are going wrong and how to correct that error so that you can move forward.
If you tried to measure AC current with an AC meter, then the meter would show a non-zero value. But if you measured AC current with a DC meter, then the DC meter would show a zero value. So to prove the given statement would you need to calculate the average DC value of the current or the average AC value of the current? How would you mathematically represent AC current?
Just wondering, are you taking a course at a school or online, or are you just studying on your own?
It helps to show some of your own work so that people know better what form of the answer would help you the most.