Which of the following is considered a renewable resource?

Trees are considered a renewable resource because they can naturally regenerate over time through biological processes. When managed sustainably, forests can provide a continuous supply of timber and other products without depleting the resource. This means that as long as trees are allowed to grow back after being harvested, they can be utilized repeatedly without exhausting the resource.

In contrast, the other options do not share the same renewable characteristics. Coal and natural gas are fossil fuels formed over millions of years from the remains of ancient organisms. Their extraction and use deplete the earth's natural reserves at a much faster rate than they can be replenished, making them non-renewable resources. Similarly, while nuclear energy is produced from uranium, which is also finite and not renewable, it cannot regenerate like trees can. Therefore, the unique ability of trees to regrow makes them the correct answer in the context of renewable resources.