1. E.

From the given conditions, we have
water: syrup: lemon juice $=4 \times 2: 2: 1$.
Therefore, Luca made a total of $3 \times 8=24$ cups of lemonade.
1. Luca sold homemade lemonade at a school fundraiser. In the process, the water he added was 4 times the amount of syrup, and the syrup was 2 times the amount of lemon juice. He used 3 cups of lemon juice, so he could make ( ) cups of lemonade.
(A) 6
(B) 8
(C) 12
(D) 18
(E) 24