The correct option is D ancestral giraffes with slightly longer necks than other got more food and left more surviving offspring
According to Darwin theory, there is both long and short neck giraffe due variation in the population. When there is a shortage of short tree leaves, short neck giraffe died and long neck giraffe survive.
Hence, the correct answer is 'ancestral giraffes with slightly longer necks got more food than others and left more surviving offspring'.