Refer to the input text as context and select the correct relationship between 'Aurizon' and 'coal' from the available options.
Options: operator, employer, manufacturer, product/material produced

Prescott quietly slipped out of Aurizon last week, and the public formalities of Monday's obviously solid annual results announcement provided a timely platform for chief executive Lance Hockridge to reassert a recovery of focus on his core coal business and on sating senior owners' expectations that he is running an annuity investment.
product/material produced