177.Bihar is India’s poorest state, with an annual per capita income of $111, lower than in the most impoverished countries of the world. (A) lower than in (B) lower than that of (C) and lower than that of (D) which is lower than in (E) which is lower than it is in 我想问下答案B,能否用lower than that in 呢?????表示lower than the income in the most ....countries,我觉得也通的呀 因为看到有的时候比较级后面补充that of/those of,但是不知道这个of为何要加上去,求指教!!!