The geologist time scale was formed when scientists studied rock layers and index fossils worldwide. With this information, they placed Earth's rocks in order by relative age. Later, radioactive dating helped determine the exact age of the divisons in the geologic time scale.
This scale is organized by the 4.6 billion years of earth's history into sections based on important changes seen in the geologic record. The largest intervals are called eons, with each eon containing many millions of years.
In precambarian time the processes that affect Earth's surface have lessened the erosion on the surface. Earth was being hit by meteorites every second. Now there is water erosion and there wasn't back then. The surface changes have lessened over time.
        
                    
             
        
        
        
A sperm and egg combine to make a zygote. (or fertilized egg) 
So, the answer would be "A".
I hope this helps!
~cupcake
        
             
        
        
        
It is called the homeostasis.
Homeostasis is the living organism's mechanism to maintain and sustain its internal environment at the level where it will suffice for them to survive. This process involves the pulling and pushing of delinquencies and extremities with an organism. 
        
                    
             
        
        
        
Connell's famous barnacle experiment was initiated to learn more about competitive exclusion and distribution of branacle species. Barnacle species are distributed in distinct zones on the rocky shores of the Atlantic coast. The Chthamalus in upper intertidal zone; is a smaller species and the semibalanus in low intertidal zone which is a larger species. Chthamalus found in the higher physical stress and higher temperatures because the low tide levels causes them to be exposed to the extreme outside environment for longer periods of time than the semibalanus. Additionally barnacles can only feed while submerged and the higher up shore a barnacle is, the less it can feed and grow. The experiment wanted to understand why they lived this way.
        
             
        
        
        
We are living in the quaternary period