Answer:
In biology, evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. ... Evolution relies on there being genetic variation in a population which affects the physical characteristics (phenotype) of an organism.
Explanation:
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All of these things are caused by Genes, so your answer is A. When two reproductive cells fuse, their traits are either dominant, or recessive. Dominant traits are displayed.
Answer: B. Water breaks down into oxygen molecules for respiration.
Water is the required for photosynthesis, a process by which plants (terrestrial and aquatic) makes their food by utilizing water as a reactant to produce oxygen and glucose as product. The glucose act as a source of energy for conducting various metabolic processes in plants but oxygen is released in the air.

This oxygen is necessary for terrestrial and aquatic animals for respiration. Therefore, water breaks down into oxygen by the process of photosynthesis, hence water plays important role in respiration in living beings.
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