Blood is related to Pale. Pale is related to Skin. Skin is related to Protective. 
Sell is a type of Exchange. Exchange is related to Change. Change is related to Pocket. 
Blood <--RelatedTo--> Pale <--RelatedTo--> Skin <--RelatedTo--> Protective 
Sell --IsA--> Exchange <--RelatedTo--> Change <--RelatedTo--> Pocket 