根据以下内容，回答题。
Passage One
There has been， in history， a man who was swallowed by a whale and lived to tell the tale. The man"s name is James Bartley. The records to prove his unusual experience are in the British Admiralty.
Bartley was making his first trip on the whaling ship Star of the East. Suddenly the lookout sighted a huge sperm whale. The whalers knew it was a huge whale by the size of the spray it blew into the air. They lowered their small boats. James Bartley was in the first longboat. The men rowed until they were close to the whale. A harpoon was thrown and it found its mark. It sank into the whale"s flesh. The maddened beast crashed into the boat， snapping its tail at the men and the wreckage of their boats. When the survivors were picked up， James Bartley was missing.
Shortly before sunset， the whale was finally captured. The sailors tied the whale"s dead body to the side of the ship. Because of the hot weather it was important that they cut up the whale right away. Otherwise， the meat would begin to rot and oil would begin to spoil. When they got to the stomach， they felt something moving about wildly. They thought it would be a big fish still alive inside. But when they opened the stomach they found James Bartley. After this trip， Bartley settled in England， and never returned to sea.
This passage is mainly about__________. 查看材料

A. how to hunt whales for their oil and meat
B. The hard and dangerous lives that whalers had to live
C. The duties of each man on a whaling ship
D. a man who was swallowed by a whale and lived