Explanation:
A keystone species is an organism that helps define an entire ecosystem. By keeping populations of mussels and barnacles in check, this sea star helps ensure healthy populations of seaweeds and the communities that feed on them—sea urchins, sea snails, limpets, and bivalves.
Answer:
If you decided that the continuous spectrum of earlobe shape was a more accurate way to describe the variation, you aren’t alone. Family and genetic studies show that earlobe attachment is actually not a simple trait, but rather a complex trait, affected by multiple genes and environmental factors.
I believe it is D, all of these. :) I hope this helps! Please tell me if I'm wrong :)
O positive is the most common blood type and most likely to be transfused.
O negative donors are the “Universal Donor.” People with O negative blood are universal red blood cell donors. This means that their red blood cells can be transfused to any blood type.
