Once a group of 17-year-old schoolboys decided to break the world basketball marathon record. They wanted to play for 90 hours ,breaking the record by adding 6 hours . Each team had 9 players, with 5 at a time. The boys decided each person would play 21.5 hours and then rest for 2 hours. Then they started at 6 o'clock in the evening. The first night was very hard for the players. When it was their turn to rest, they were too excited to fall asleep at once. On the second night,they fell asleep as soon as they stopped.Some of them had trouble with their feet and hands, but the only serious problem was a psychological one. Each boy was thinking: Why am I doing this? How can I play any longer? After the third night, the players knew they could finish the 90 hours. The basketball on the fourth nigth was very slow. But in the final hours, the players got better. For the last few minutes, How happy everyone was! Before this basketball marathon, the world record was    _    .
84 hours 86 hours 90 hours 96 hours