Treat is related to Chocolate. Chocolate is related to Bitter. Bitter is related to Like. 
Specialize is a synonym of Narrow. Narrow is a type of Change. Change is related to Vary. 
Treat <--RelatedTo--> Chocolate <--RelatedTo--> Bitter <--RelatedTo--> Like 
Specialize <--Synonym--> Narrow --IsA--> Change <--RelatedTo--> Vary 