I recall how ______ it was years

I recall how ______ it was years ago when people littered everywhere in our city.
A、annoying
B、scaring
C、frightening
D、humiliating
【正确答案】：A
【题目解析】：annoying恼人的；scaring令人害怕的；frightening令人恐惧的；humiliating丢脸的，羞辱性的。句意：我还记得几年前我们城市里到处都是人，那是多么令人讨厌。