Your company currently uses a standard PSTN communication link to transfer files between LANs. Until now, the transfer speeds have been sufficient for the amount of data that needs to be transferred. Recently, a new application was purchased that requires a minimum transmission speed of $1.5 \mathrm{Mbps}$. You have been given the task of finding the most cost-effective solution to accommodate the new application. Which of the following technologies would you use?
A. T3
B. $X .25$
C. $T 1$
D. BRI ISDN