Moral is related to Good. Good is related to Effort. Effort is a type of Labor. Labor is a synonym of Dig. 
Choose is related to Opt. Opt is the opposite of Join. 
Moral <--RelatedTo--> Good <--RelatedTo--> Effort --IsA--> Labor <--Synonym--> Dig 
Choose <--RelatedTo--> Opt <--Antonym--> Join 