Explain is related to Communication. Communication is related to Radio. Radio is related to Toy. Toy is related to Little. 
Mountain is related to Like. Like is a synonym of Preference. 
Explain <--RelatedTo--> Communication <--RelatedTo--> Radio <--RelatedTo--> Toy <--RelatedTo--> Little 
Mountain <--RelatedTo--> Like <--Synonym--> Preference 