Answer: C. Seeds
Biotic factors are the living components of an ecosystem. These includes living beings and components ,which are the precursors of life. Plants, animals, microorganisms are examples of biotic factors. Coastal ecosystems are areas where land and water meets. Therefore, this supports the life of both terrestrial and aquatic life forms. Seeds are the biotic factor in a coastal ecosystem as these are the precursors of plant life. Seeds will germinate to give birth to new plants.
