请教陈向东逻辑中的一道题

Once the economic and social usefulness of the motor car was demonstrated and with its superiority to the horse being proved, much of the early hostility to it in rural regions disappeared.

B.and its superiority over the horse had been

D.its superiority over the horse

答案是B。但是我觉得好象是D对。因为B没有任何时间标志表明它应该用had been，逻辑上也讲不通这个动作发生在was demonstrated前面。

而D的was 因为并列关系所以可以省略。不知道我的理解对不对呢？还望NN指点。