Apology is related to Regret. Regret is the opposite of Confident. Confident is related to Certain. 
Corporation is related to Enterprise. Enterprise is related to Company. Attendance is a type of Company. Presence is a type of Attendance. 
Apology <--RelatedTo--> Regret <--Antonym--> Confident <--RelatedTo--> Certain 
Corporation <--RelatedTo--> Enterprise <--RelatedTo--> Company <--IsA-- Attendance <--IsA-- Presence 