Rear is related to Demand. Challenge is a type of Demand. Challenge is related to Risk. 
you are likely to find Teaspoon in/at/on Tea. Tea is related to Hot. Hot is similar to Eager. 
Rear <--RelatedTo--> Demand <--IsA-- Challenge <--RelatedTo--> Risk 
Teaspoon --AtLocation--> Tea <--RelatedTo--> Hot <--SimilarTo--> Eager 