A zookeeper is a person who manages zoo animals that are kept in captivity for conservation or to be displayed to the public. They work very closely with all the animals in the zoos and have many responsibilities to maintain the health and wellness of each animal. They must have good record keeping skills since there is a lot of data that must be collected for each animal. Each species is different from each other and requires special attention and care that a zookeeper must give. Zookeepers also have a very interesting history that starts in B.C. and continues to the present day.

Which of the following means the opposite of the word “captivity” as it appears in the passage above?