Opt is a synonym of Select. Select is a synonym of Prime. Prime is a synonym of Principal. Criminal is a type of Principal. 
Key is a type of Explanation. Proof is a type of Explanation. Proof is related to Argument. Pro is a type of Argument. 
Opt <--Synonym--> Select <--Synonym--> Prime <--Synonym--> Principal <--IsA-- Criminal 
Key --IsA--> Explanation <--IsA-- Proof <--RelatedTo--> Argument <--IsA-- Pro 