The answer is D. The natural selection is a theory which illustrates the gradual process of evolution in the population due to the change of environment. The key point is the mutation (variation) exists in the population before the environment changing. For C, if the environment does not change, though the adaptation is useful to environment, it will not be selected. Because the organisms without the adaptation will not die.
Around 3-4% is the answer.
Cellular respiration is the process by which cells in plants and animals break down sugar and turn it into energy, which is then used to perform work at the cellular level. The purpose of cellular respiration is simple: it provides cells with the energy they need to function. If living things could not get the energy they need out of food, it would be absolutely worthless. All living things would eventually die, no matter the quality and amount of food.
C6H12O6 + 6O2 → 6CO2 + 6H2O (glucose + oxygen -> carbon dioxide + water)
The products of photosynthesis, oxygen and glucose, are the reactants of cellular respiration. The products of cellular respiration, carbon dioxide and water, are the reactants of photosynthesis.
Thymine, is the answer you’re looking for.