Which of the following describes non-renewable resources?

Non-renewable resources are defined as natural resources that exist in finite amounts and do not replenish at a sustainable rate once they are depleted. This means that the rate at which these resources are consumed far exceeds the rate at which they can be naturally regenerated. Examples of non-renewable resources include fossil fuels like coal, oil, and natural gas, as well as minerals such as gold and copper. Once extracted and utilized, the remaining reserves diminish and, consequently, can take millions of years to form again, if they form at all.

The other responses are not accurate descriptions of non-renewable resources. For instance, resources that replenish naturally at a fast rate describe renewable resources, which can be regenerated within a human time scale, such as biomass or solar energy. Resources that can be harvested indefinitely also pertain to renewable resources, as they are capable of being replenished as they are used. Lastly, resources that are completely synthetic do not fall under the category of non-renewable resources since they are artificially created and not extracted from the environment in the same manner as natural resources. Thus, the distinction lies clearly in the unsustainable replenishment rate characteristic of non-renewable resources.