Utility is related to Bill. Bill is related to Debt. Debt is related to Deficit. 
Opportunity is the opposite of Door. Door is related to Protection. Lock can be used for Protection. Lock is related to Drawer. 
Utility <--RelatedTo--> Bill <--RelatedTo--> Debt <--RelatedTo--> Deficit 
Opportunity <--Antonym--> Door <--RelatedTo--> Protection <--UsedFor-- Lock <--RelatedTo--> Drawer 