Environment custom field is a multi-option field. Each Environment is represented by a specific Option having different properties (eg: category name, application name, etc.). Environment is an asset part of your Golive Environment Inventory, and Options are their copy in your Jira instance. On your issues, when you select a value for an Environment Custom Field, you select an option which refers to an Environment in your inventory. This means options must be maintained, synchronized, to represent the status of your Environment inventory. For example, each time an environment is created/deleted, its corresponding option is created/deleted as well.