Answer: A. Increased population
Step-by-step explanation:
Resources can be man-made or natural it depends upon their sources. These resources are required by the people to meet the needs of their daily lives. Some of the renewable resources such as water, wind and others can be replenished and reused after a single use. But some non-renewable resources like coal, petroleum and others cannot be reused after a single use.
With the increase in the population world wide, the demand for resources likely to increase and the rate of consumption of the resources will also increase. This will ultimately lead to decrease in concentration of these resources.