gwd-9-3 提出新疑问

Because of wireless service costs plummeting in the last year, and as mobile phones are increasingly common, many people now using their mobile phones to make calls across a wide region at night and on weekends, when numerous wireless companies provide unlimited airtime for a relatively small monthly fee.

A. Because of wireless service costs plummeting in the last year, and as mobile phones are increasingly common, many people

B. As the cost of wireless service plummeted in the last year and as mobile phones became increasingly common, many people

C. In the last year, with the cost of wireless service plummeting, and mobile phones have become increasingly common, there are many people

D. With the cost of wireless service plummeting in the last year and mobile phones becoming increasingly common, many people are

E. While the cost of wireless service has plummeted in the last year and mobile phones are increasingly common, many people are

看过汇总里的两个讨论帖，都是围绕着D和E。不禁想问，为什么没人提到B呢？B里面and两边的对称很好啊，时态也很对，它错在哪里呢？至于逻辑关系，我认为用因果关系是通顺的，而且原句也是因果关系，所以应该因果关系优先。而用while就是让步或转折的了，我觉得没十二分必要不应改两分句间的关系