Which of the following best explains why air is considered a natural resource?
a. air is expensive to produce and keep clean.
b. air is a raw material for biological processes supplied by the earth.
c. air can be processed to generate expensive chemicals.
d. none of the above

I would actually say it's b. on the grounds that it is the only answer that refers specifically to it being supplied by the earth, thereby making it naturally occuring 

The haitian revolution was the result of a long struggle on the part of the slaves in the french colony of st. domingue, but was also propelled by the free mulattoes who had long faced the trials of being denoted as semi-citizens. this revolt was not unique, as there were several rebellions of its kind against the institution of plantation slavery in the caribbean, but the haitian revolution the most successful. this had a great deal to do with the influence of the french revolution, as it to inspire events in haiti. the haitian revolution would go on to serve as a model for those affected by slavery throughout the world.