An eligible employee who returns to work after taking parental leave is entitled to be restored by an employer: to the position of employment held by the employee when the parental leave began; or to an equivalent position with equivalent employment benefits, pay, and other terms and conditions of employment. An employer may: deny restoration of the eligible employee’s position of employment under subsection (a) of this section if: the denial is necessary to prevent substantial and grievous economic injury to the operations of the employer; the employer notifies the employee of the intent of the employer to deny restoration of the employee’s position of employment at the time the employer determines that economic injury would occur; and in a case of parental leave that has already begun, the employee elects not to return to employment after receiving notice of the employer’s intention to deny restoration of the employee’s position of employment; and during the parental leave period, terminate employment of an eligible employee only for cause.