看下这道高中英语单选题After being turned down several times,the young m

看下这道高中英语单选题
After being turned down several times,the young man felt _____ at the thought of looking any further for jobs.
A) embarrassed B) disappointed C) startled D) discouraged
这道题选什么呢?B还是D?我觉得两个都可以,一个是失望,一个是失去信心.
被拒绝了几次以后,这个男的对找工作失去了信心.
被拒绝了几次以后,这个男的对找工作充满了失望.
我觉得都可以,可是答案是B,我选的是D.从那看出来D不对?