Sock is related to Article. Article is a synonym of Object. Object is related to Line. Line is related to Ship. 
Answer is related to Test. Test is a synonym of Run. Exercise requires Run. 
Sock <--RelatedTo--> Article <--Synonym--> Object <--RelatedTo--> Line <--RelatedTo--> Ship 
Answer <--RelatedTo--> Test <--Synonym--> Run <--HasPrerequisite-- Exercise 