此题的正确答案是：【D.other things being equal】
这是独立主格结构作条件状语的,等于：If other things are equal
Other things【being】equal,a man who can express himself effectively is likely to succeed more rapidly than those who can't.
being 可省.
语言点：
当独立主格结构中being 后面的逻辑表语是形容词,副词,不定式,介词短语时,being 可以省略
如：
The boy is playing with snow,hands (being) red with the cold.（形容词）
He came in,book in hand (介词短语）
The meeting (being) over(副词）,they walked out of the room.
不能省的两种情况
There + be 句型
如：There being no buses,we had to walk home
当逻辑表语是名词时
The boy being a student,we should do what we can to help him
【翻译】：如果其它情况一样,那么善于有效表现自己的人有可能比那些做不到这些的人先一步到达成功的彼岸