D. In the bottle was... 1. A piece of paper. 2. A rock. 3. A coin. 4. Nothing.

Обоснование: В тексте сказано: "Then a sailor took a large knife and opened the fish. Inside its belly, there was a bottle. 'Sometimes bottles found at sea contain very interesting documents,' exclaimed Lord Glenarvan. Lord Glenarvan was right. Inside the bottle was a piece of paper.". Это прямо указывает на то, что в бутылке был кусок бумаги.

Ответ: 1. A piece of paper.