What is formed by groups of cell which work together as organs in organ systems

An organ system is made from a group of different organs, which all work together to do a particular job. Here are some examples of organ systems:

it cools slower in the earth meaning the crystals have more time to form than lava on the surface

kelp are large brown algae that live in cool, relatively shallow waters close to the shore. they grow in dense groupings much like a forest on land. these underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

e) all of the above