A termination of a worker's employment is fair if the contract of employment is terminated by the employer on any of the following grounds:

(a) that the worker is incompetent or lacks the qualification in relation to the work for which the worker is employed;

(b) the proven misconduct of the worker;

(c) redundancy under section 65;

(d) due to legal restriction imposed on the worker prohibiting the worker from performing the work for which he or she is employed.