The correct answer is B, 2 liters. This is water only. If you count food and other beverages a breastfeeding mother should have nearly 4 liters (3.8) of fluids per day. If the woman drinks coffee or other caffeinated drinks the caffeine will pass through to the breastmilk and can make the baby jittery. These beverages if ingested should be limited to 1 or 2 a day if not offset by other fluids.
I believe it is B. 2 Liters