As the human population grows, our natural resource requirements increases. The answer is letter A. One, the source of food is important for survival. More humans needed the right nutrition to improve bodily functions. And therefore, more lands are to be cultivated for agricultural production to suffice the needs of the society. Two, humans need extra habitable area to live. It does not go in cycles because the ecosystem is not balanced. Population explosion is the main cause why these natural resources slowly decreases and at the same time increases their demand.