Verbal is the opposite of Written. Written is related to Reply. Reply is the opposite of Request. Apply is a type of Request. 
Enforcement is related to Policeman. Policeman is related to Guard. 
Verbal <--Antonym--> Written <--RelatedTo--> Reply <--Antonym--> Request <--IsA-- Apply 
Enforcement <--RelatedTo--> Policeman <--RelatedTo--> Guard 