Regional is related to District. District is related to Board. Board is related to Grain. 
Join is the opposite of Quit. Quit is a synonym of Depart. Depart is related to Arrive. 
Regional <--RelatedTo--> District <--RelatedTo--> Board <--RelatedTo--> Grain 
Join <--Antonym--> Quit <--Synonym--> Depart <--RelatedTo--> Arrive 