Answer: D. the tides
A salt marsh is a biome located in the coastal region. It is an intermediate zone between the land and seawater. It is mainly dominated by the salt tolerating plants such as grasses, herbs and shrubs. The salt marshes delivers nutrients to the coastal water and the terrestrial animals also feed upon plants of the salt marsh. The salt marshes are influences by the high and low tides of the sea water. These tides bring a change in the salinity of water in which the plants of the salt marsh are growing. Some plants which are tolerant to drastic changes in the salinity survives whereas those which are not capable they die.