请教og50 糊涂.

50. As a baby emerges from the darkness of the womb with a rudimentary sense of vision, it would be rated about 20/500. or legally blind if it were an adult with such vision.

(A)  As a baby emerges from the darkness of the womb with a rudimentary sense of vision, it would be rated about 20/500, or legally blind if it were an adult with such vision.

(B)  A baby emerges from the darkness of the womb with a rudimentary sense of vision that would be rated about 20/500, or legally blind as an adult

(C)  As a baby emerges from the darkness of the womb, its rudimentary sense of vision would be rated about 20/500; qualifying it to be legally blind if an adult

(D)  A baby emerges from the darkness of the womb with a rudimentary sense of vision that would be rated about 20/500; an adult with such vision would be deemed legally blind.

(E)   As a baby emerges from the darkness of the womb, its rudimentary sense of vision, which would deemed legally blind for an adult, would be rated about 20/500.  

我就是觉得B 和D 之间虽然有区别,但;号的作用不是很清楚,而且觉得og上说B用词含糊,我想不通,请大牛指点!

始终想不通B为什么错了.

(B)  A baby emerges from the darkness of the womb with a rudimentary sense of vision that would be rated about 20/500, or legally blind as an adult

that指a rudimentary sense of vision
因此後面接的 or legally blind as an adult 主語是a rudimentary sense of vision
邏輯不通.. sense of vision=an adult??

感觉上，or前有没有逗号都无所谓吧。：）

i gree

关于B选项中的逗号问题，我是这样看的：

A baby emerges from the darkness of the womb with a rudimentary sense of vision (that would be rated about 20/500, (or legally blind as an adult))

or前面的逗号使legally blind as an adult与前面的rated about... 的关系松散了很多，如果or legally blind as an adult与with...并列修饰a baby emerges from the darkness也从语法上讲不通.

退一步,如果这里没有逗号, 则that would be rated about 20/500 or legally blind as an adult 是在一起修饰vision的定语从句的话, 又从逻辑上讲不通. 这样就是等于说vision is blind. 而不是人blind.

总之,怎么解释这个逗号都不能使B成为正确选项的.

弱弱的请教一句，句中的 20/500 是指什么？

百分比？比例？