Option key (stored in c.state when picked).
Label shown in the numbered menu.
1-based menu number the user types.
OptionalthenWhat runs when picked: an inline sub-flow, an action, or nothing (absent).
OptionalthenId of the inline sub-flow, when then === 'flow'.
OptionalgotoConversation the option jumps to ({ goto }), after its then if both are set.
One option of a
choosenode.