You need to ensure that there is adequate bandwidth available to meet the service-level agreement requirements. Which action or actions should you perform？ （）

A. Upgrade all WAN lines in six months.
B. Upgrade all WAN lines prior to implementing NewApp.
C. Analyze the cause of a peak in network usage in February.
D. Analyze network usage characteristics for NewApp.Based on these results， create an upgrade plan for the WAN lines.