Natural is a synonym of Necessary. Necessary is related to Must. Must is related to Demand. 
Charter is a synonym of Rent. Rent is a different concept from Own. Own is related to Claim. 
Natural <--Synonym--> Necessary <--RelatedTo--> Must <--RelatedTo--> Demand 
Charter <--Synonym--> Rent <--DistinctFrom--> Own <--RelatedTo--> Claim 