The first issue you need to be aware of is pronoun reference. It should be employees’ legal right, not employers’. Therefore, you can eliminate A and D. The singular “an employee” does not go together with the plural “their”. Option B does not have greement between the plural “employees” and the singular “he”. Option E has an unclear pronoun, “they”, at the end of the option. It is not clear whether this word refers to the employees or the employers. Only option C is correct.