Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Figure 12.7 Statues made from carbonate compounds such as limestone and marble typically weather slowly over time due to the actions of water, and thermal expansion and contraction. However, pollutants like sulfur dioxide can accelerate weathering. As the concentration of air pollutants increases, deterioration of limestone occurs more rapidly. (credit: James P Fisher III). Answer: air pollutants
[EX A]: Deterioration of limestone occurs more rapidly as the concentration of what increases?

[EX Q]: Passage: Segmented worms include the common earthworm and leeches. Answer: segmented
[EX A]: The common earthworm and leeches are examples of what type of worm?

[EX Q]: Passage: Renewable resources can be renewed as they are used. An example is timber, which comes from trees. New trees can be planted to replace those that are cut down. Sunlight is a renewable resource. It seems we will never run out of that!. Answer: renewable
[EX A]:
Timber, obtained from trees that can be replanted to replace those that are cut down, is an example of what type of resource?