How is natural selection in the evolution of long necks in giraffes best explained?

Giraffes probably used to have short necks. Over time, since the branches of trees or plants were out of their reach, they adapted to this by having a longer neck. Those with longer necks are able to reach the food and eat it that those with short necks could not. Obviously, those with longer necks are able to survive and therefore reproduce. Because of reproduction, they are able to pass on this characteristic that allowed them to survive on to their offspring. This leads to offspring doing the same and over time, affecting the entire population of giraffes and soon evolving giraffes. This is natural selection doing its work in the evolution of long necks in giraffes.

They must use the scientific method

Sugar + oxygen > carbon  dioxide + water + energy  c6h1206 + 6o2 > 6co2 +6h2o + energy  and the numbers after the element symbols are small.