Advertisement A: "Buy two bottles of soda and get one soda free" seems more reasonable.
This offer is typical in promotions for beverages, where buy-one-get-one deals or similar discounts are common.
On the other hand, Advertisement B: "Buy two bottles of soda and get a free trip to Disney World" is highly improbable and unrealistic, as the cost of a trip to Disney World far exceeds the price of two bottles of soda.