Ecosystems can be large and are made of biomes. Some examples of ecosystems are deserts and forests.
I believe it is muscle cells, I'm sorry if this is incorrect.
Answer:Tissue
Explanation:Heart muscle cells beat in unison to push blood in timing with the rhythm of the heart, at the direction of nearby nerve cells. These muscle cells could best be called. Tissue. As cell division proceeds, the cells increase in number, but also become specialized in structure and function.
For this item, I would go with letter "D. physical destruction of marine habitats". Many of the modern ways of fishing poses an irreversible destruction to marine habitats. These practices include trawling, lining methods, purse seining, etc.