It is a legal ______ for parents to ensure that their children are provided with efficient education suitable to their age.
 
【正确答案】 B
【答案解析】 sympathy“同情,同情心”;obligation“义务,责任”;impulse“冲动,刺激”;influence“影响,感化”。根据句中legal提供的语境,parents to ensure...children...是一种义务,故答案为8。