It might be 23% because 77% of water covers earth and most of the water is either polluted or salt water.
I believe the term for an observable trait of an organism would be called or noted as the organism's phenotype.
All above I think I don't know
Answer:
nuclear fusion
Explanation:
When the density and temperature at the core of the gravitationally collapsing nebula reaches values when nuclear fusion is triggered and sustained, that marks the birth of the star.