The answer to the first question is D. but I'm not sure about the second question
The best answer would be it has happened because of natural selection.
Over many generations, natural selection selects the traits that bring advantages to it's holders. In the case of the horse ancestors, the traits selected were all adaptation to living in the steppe, the vast grasslands.
Over time, the individuals who could run the fastest and avoid the predators and utilize the resource that is most available in the grasslands- grass would be the most successful, leave more offspring and eventually be more prevalent in the population.
<span>Electron Transport Chain</span>
Answer:The ER also contains domains that contact the plasma membrane (PM) and other organelles including the Golgi, endosomes, mitochondria, lipid droplets, and peroxisomes.
From a hot body as a result of its temperature