Which physical feature is located in the coastal plain and was designated as a national wildlife refuge to protect the diverse plants and animals that live there? A) The barrier islands
B) The Okefenokee Swamp
C) The Appalachian Mountains
D) The Fall Line

The physical feature located in the coastal plain and designated as a national wildlife refuge to protect the diverse plants and animals that live there is:

B) The Okefenokee Swamp

Explanation:

The Okefenokee Swamp refuge was established in 1937 but designated a refuge of wildlife in 1974 for the numerous plants and animals that inhabit it.  It covers an area of ‎438,000 acres (1,770 km2)  and is located in the Southern Georgia and Northern Florida States of the United States.  It is also considered to be one of the seven natural wonders of Georgia.