Which solution eliminates the need for dedicated high-speed WAN connections between sites

Wireless WAN like VSAT and WIMAX.

Explanation:

WAN or wide area network is a form of network meant for long distance communication between sites. It is made up of interconnecting local area networks spanning from a town to global communication of branches in an organisation.

For local area networks to be connected together to make a WAN, a dedicated high speed cable connection must be installed between sites. Fiber optics, among others, is the widely used dedicated WAN backbone connection. Cable connections are faster and moderately secure.

A VSAT is a wireless network connection method, where networks are connected using satellite dishes in remote networks, in the line of sight to a satellite, for WAN communication. It is not as fast or as secure as the cable connection, but can be used in remote area, where ISP in not available.