Final answer:
Charles Darwin would have disagreed with the idea that stretching and the inheritance of acquired characteristics could lead to the evolution of longer trunks in elephants and giraffes, based on his theory of natural selection and his observations.
Step-by-step explanation:
Charles Darwin would have disagreed with the statement that elephants lengthened their trunks by stretching and passed this trait to their offspring, resulting in the evolution of longer trunks in the giraffe population. Darwin's theory of evolution by natural selection states that traits are not acquired through use or stretching, but rather through genetic variation and natural selection.
Darwin observed that variation in the length of necks existed in giraffes, and those with longer necks had an advantage in accessing leaves higher up in trees. As a result, giraffes with longer necks were more likely to survive and reproduce, passing on this advantageous trait to their offspring. Over time, the population would consist mostly of giraffes with long necks.
Therefore, based on Darwin's theory of natural selection and his observations, he would have disagreed with the idea that stretching and the inheritance of acquired characteristics could lead to the evolution of longer trunks in elephants and giraffes.