Final answer:
The floodway is defined as the stream channel and that portion of the adjacent floodplain that must remain open to permit passage of the base flood.
Step-by-step explanation:
The correct answer is b) Floodway.
The floodway is defined as the stream channel and that portion of the adjacent floodplain that must remain open to permit passage of the base flood. It is designed to carry the majority of the floodwater and is usually a narrow area. The floodplain zone refers to the entire area that may be flooded during a base flood, including both the floodway and the adjacent floodplain. The buffer zone is a term used in environmental science to refer to a protective area around a sensitive habitat or resource. The flood hazard area encompasses both the floodway and the adjacent floodplain, but it is not the specific term used to define the stream channel and adjacent floodplain.