Dispute is the opposite of Confirm. Prove is a type of Confirm. Prove is related to Must. 
Protective is related to Defensive. Defensive is related to Guard. Guard is related to People. 
Dispute <--Antonym--> Confirm <--IsA-- Prove <--RelatedTo--> Must 
Protective <--RelatedTo--> Defensive <--RelatedTo--> Guard <--RelatedTo--> People 