Which of the following is NOT a valid reason for deducting an employee's wages?

The choice concerning insufficient work is not a valid reason for deducting an employee's wages because wage deductions require a legally justified reason or agreement. Employers cannot simply reduce wages based on fluctuations in work amounts unless specific agreements or conditions are in place, as this could lead to unfair labor practices and violate employee rights.

In contrast, wage deductions for labor union dues are typically authorized through collective bargaining agreements, making them valid. Likewise, legal authorization and employee consent also provide acceptable grounds for deductions, as they involve adherence to legal standards or mutual agreements between the employer and employee. Therefore, insufficient work lacks the legal or consensual basis that justifies wage deductions, making it the correct answer.