The sun rays are received by the plants and explell oxygen and we breath the oxygen to be able to survive 
        
             
        
        
        
Crossing over occurs at the four-strand stage when two homologous chromosomes, each consisting of a pair of sister chromatids, are paired. Each crossover involves just two of the four strands and generates two recombinant strands.
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Answer:
In speciation, organisms evolved with the passage of time.
Explanation:
Speciation is the evolutionary process in which populations of species evolve with the passage of time to become different species from the original one.  Temporal isolation and gametic isolation are two possible prezygotic barriers of the Hawaiian honeycreepers that contribute to occur speciation. The newly available niches could lead to speciation of that organisms that tolerate the Hawaiian climatic conditions when the extinction of Hawaiian honeycreepers occurs. The new organisms used the available resources such as food and space etc and increase its population.
 
        
             
        
        
        
<span>The correct answer is A. water. That's because water's chemical composition is such that it can't be decomposed and turned into a fuel. Unlike Corn, sugar cane, and wood, it can't be used to power machines. The other ones are organic and can be used as biofuel, while wood can even be used in the form of coal as coal is nothing else than wood.I hope that my answer is helpful! Let me know if you need something more :)</span>