[求助]本月JJ……快考了…..求救

sihua

请问这题NN们怎么看

5.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

答案：A   WHY NOT b

Springfield

晕倒，我都以身试法了，法的帖子你居然不去看，肯定是D；不知道楼主和CD上个各位是怎么了？ 难道总是需要别人把现成的答案送到嘴里？