What is required by a lockout/tagout procedure? a that the presence of hazardous chemicals be clearly labeled in the workplace b that employees who operate dangerous equipment have training to use that equipment c that an employee who is beginning a shift check in with the managers and the employee that is being relieved d that when servicing equipment that may release dangerous energy when started up, employees must clearly indicate with signs that the equipment should not be turned on and in some cases that the equipment must be disabled using locked devices