Some card effects can lead to various types of events, and one event type is Choice. Usually, the card has a Story text at the top, which a player other than the currently active player reads out aloud. Then the event type is indicated in the middle of the card, and when the event type is Choice, the player who read the Story text continues to read the names of the alternatives given in the lower half of the card, but keeps the effects of those alternatives secret. The active player then chooses one of the alternatives, and the effect of that alternative is applied.
Cards that typically can offer such choices are Sea Event cards, Expedition cards and Denizen cards.
Story
The game has a set of Story cards which are numbered, and which can be triggered by other cards telling the player to locate a Story card with a specific number. This can potentially lead to another Story card being fetched, and so on, until the Story is resolved. There may be conditions connected with the advancement of a Story, and if the conditions are not met, the Story can end without being resolved.
Stories can be initated by Sea Event cards, Expedition cards and Denizen cards; those cards may trigger some Skill Test or choice, whose outcome text includes a number surrounded by pluses (like "+13+"). In such cases, locate the correspondingly numbered Story card from the Story deck, and place it under the Ongoing Story cover card without resolving it, and place the card that instructed you to fetch the new Story card in the Story area of the Ship Board for the player who caused the event to happen (usually the player whose turn it is).
The newly fetched story card will stay under the Ongoing Story cover card until an End of Act puts it back into play.