Salt marshes are coastal lands that are filled and run out by seawater taken in by the periodic event. The incorrect option about the salt marshes is that the salt marshes are not productive habitats.
A salt marsh is also known as the coastal salt marsh or a tidal marsh. It is a coastal ecosystem in the higher coastal seacoast zone between land and opened seawater or brackish water that is on a regular basis swamped by the recurrent event.
Historically they were run out for agriculture and drained for agriculture, and here the remaining marshes are severely degraded.
Therefore, option C is correct.
Learn more about the salt marshes, refer to:
https://brainly.com/question/756092