To the naturalistic writer, man is
an angel
a devil
an animal
a god

The word that completes the sentence, "To the naturalistic writer, man is .", is a devil. Thus, the answer is the second among the given choices. The naturalists rejects idea or realities that cannot be supported, measured or detected by human senses. They view that human inherits their main features from the natural way and rights.

Generally spontaneous human combustion is something that still bewilders some, human combustion happens very rarely and doesn't affect the surrounding areas, so unless you want to set your self on fire, human combustion will remain spontaneous and very rare.