(a)
(1) If it shall become necessary to reduce the personnel of any department reduction shall be from the lowest rank, seniority having priority.
(2) In the event the personnel is subsequently increased, any employee who has been transferred to another department or discharged by reason of the reduction shall have seniority rights over any other employee or any applicant for employment to any position created on account of the increase in personnel.
(b) If the personnel of any department is reduced by reason of the transfer of any duties of one department to another department, any person so discharged shall have priority in the department to which the duties are transferred over any employee performing the duties who does not have a seniority rating at least equal to the person relieved on account of the transfer of the duties and over any applicant for employment covering the duties.
(c) When a vacancy occurs in any department, any employee of the same classification in any other department, seniority having priority, shall have the option of transferring to the vacancy in the department.