请教GWD9-Q3

GWD-9-Q3:

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.

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

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

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

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

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

E相较其它选项是最好的.但为什么有明显的the last year 时要用现在完成时has plummeted?

谢谢!

现在完成时的时间标志有 :since; within/during/over/in + the
past/last/recent + 时间短语

首先AB排除，因为many people后面缺少谓语动词

C的表述复杂化了，there are many people没有必要，不如many people直接做主语更简洁

D项我觉得是with的问题吧，with是介词感觉后面接的名词或名词词组不宜太过复杂。而且感觉在GMAT题中似乎不太倾向用with做状语来修饰全句的，只是个人感觉而已

另外，也同意楼上的，in the last year用完成时没有不对。并且从句意上讲，描述了到现在的状态也是合理的。

thanks very much to both of you, I get it.