Answer:
I believe the answer is, Ask other teens if they would pay to download her game. Hope this helps.
Step-by-step explanation:
I believe this because the others won't work. Asking family won't work because the might not be the same age group your trying to sell to. Doing research on how much teens play mobile games won't work because it doesn't mean a teen will pay money on a mobile game. It also won't work if you ask teens if the like her game idea because even if they like your game it doesn't mean they will pay money on it.