Final answer:
The nurse should explain that alcohol interferes with folate metabolism in the liver and supplementing with folic acid can help make up for the deficiency caused by alcohol consumption.
Step-by-step explanation:
The best response by the nurse to the client with chronic alcoholism asking why he was put on folic acid (Folvite) despite promising to stop drinking would be option 2. The nurse should explain that alcohol interferes with folate metabolism in the liver and since the client has been drinking instead of eating, he may not be getting enough folate from his diet. Thus, supplementing with folic acid can help make up for the deficiency caused by alcohol consumption.