The use of the phrase "To the careless eye" suggests that there is more to Mariposa than meets the surface, implying that only those who take the time to look closely will truly appreciate its qualities. This aligns with option D. By suggesting that observant people will appreciate Mariposa, the narrator encourages the readers to agree with their point of view. Therefore, the best answer is:
D. By suggesting that observant people will appreciate Mariposa, the narrator encourages the readers to agree with their point of view.