Lists the options of the account's dropdown, listbox, radio, and checkbox custom contact fields, 20 per page by default. Use field to list one custom field's options; that and ids are the only supported filters on this endpoint. filters[...] and orders[...] parameters are not supported here and are silently ignored, so the response looks filtered but is not. Each entry's id is a field option id: it is valid only on the fieldOptions endpoints and must never be passed to /fields/{id}, which addresses whole custom field definitions in a separate id space. Each entry's field property holds the id of the field definition it belongs to. meta.total is the number of matching options, returned as a string; it is null whenever field is set.