单项选择题
Due to limitations affecting voice quality, which of the broadband speeds shown is preferred in order to achieve highest voice quality on a converged data and voice teleworker connection?（）
A.DSL with 128k uplink /128k downlink B.cable with 256k uplink /256k downlink C.DSL with 128k uplink /768k downlink D.cable with 256k uplink /1.4M downlink
