Final answer:
The sentence suggests the author believes Keller's intelligence is due to heredity, making answer A the correct choice as it indicates the belief in natural intelligence within her family. The correct answer is A The author believes Keller and her family are naturally intelligent.
Step-by-step explanation:
The sentence "Some of the best blood of both the north and the south flows in her veins, and it is probable that her uncommon mental powers are in no small degree due to heredity." indicates that the author's point of view is that the protagonist's intelligence may be attributed to inheritable qualities, tracing back to her ancestry. This reflects the historical context where heredity was often considered a factor in a person's intellectual abilities. Thus, the correct answer to what the sentence indicates about the author's point of view is: A The author believes Keller and her family are naturally intelligent.