题目选项分析

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

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