sentence: while and with

[vscid]

Which is the correct sentence among the two?

original sentence:

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.

OPTIONS:(to replace the underlined part)

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

Please explain with reasons.

[oregeezer]

I'd use 'with'. Because my feeling is that 'while' implies that there will be a contrast.