premise: A town has exactly two public parks—Graystone Park and Landing Park—which are to be planted with North American trees. There are exactly four varieties of trees available—maples, oaks, sycamores, and tamaracks. The planting of the trees must be in accord with the following: Each of the parks is planted with exactly three of the varieties. At least one of the parks is planted with both maples and sycamores. Any park that is planted with oaks will also be planted with tamaracks. Graystone Park is planted with maples. Which one of the following must be false?
hypothesis: Both parks are planted with oaks.