In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

To a router, a flow is a (71) of packets that share the same characterstics, such as traveling the same (72) , using the same (73) , having the same kind of security, and so on. A router that supports the handling of flow labels has a (74) table. The table has an entry for each Active flow label; each entry defines the (75) required by the corresponding flow label.

（74）是（）

A. flow table

B. flow label

C. rout table

D. Tag table