Answer:
I think is C like I said not quite sure...
Well, he would use 4/4 cup of cranberry juice to equal 1 cup. that is 4x the original amount. so, multiply 1/2 × 4 to equal 2 cups. David would use 2 cups of apple juice for every 1 cup of cranberry juice.
I think c=9. I did the math...just trying to help but not exactly sure but I think it is...sorry
i uploaded a vid on this here
https://www.you tube.com/watch?v=dQw4w9WgXcQ
its actually c tho..