Because since their ancestors came before them then they inherit certain beneficial traits that help them survive. Those traits are in the DNA and the animals are evolving to be more fit for the environment that they are in. (hope this helps)
There are 3 sources of energy, which are also known as macronutrients ,carbohydrates, protein, and fat.
Of these three, carbohydrates are the body’s preferred source of energy. Carbohydrates break down into glucose, which is an immediate source of energy especially for the brain and muscles. The macronutrient proportions recommended for general, healthy diet are: 45-65% of energy (or calories) from carbohydrates, 10-20% of energy (or calories) from protein and 20-35% of energy (or calories) from fat.
I think it’s D, carbohydrates.
