A,C,F 解析：Explanation:Choice A is correct because the more hosts on a broadcast domain, the more traffic that is created. Choice Ccontributes to congestion because broadcast storms can become very problematic, and lead to complete network saturation. Multicasts are similar to broadcasts in their use on a LAN. Finally, if there is not enough bandwidth, traffic sessions can time out. This leads to new transmissions and the re-sending of data, which can lead to more congestion.Incorrect Answers:B, E. These are incorrect because full duplex operation and segmented networks actually result in less congestion.D. Multicasting can actually alleviate congestion issues, as single streams of information can reach multiple hosts at the same time, instead of using a series of point to point connections.