Final answer:
In terms of environmental costs, natural gas production is associated with the construction of pipelines through sensitive areas, methane emissions, and land degradation due to drilling techniques like fracking; however, it does not typically release trace metals during combustion, as this is more characteristic of coal burning. Option number a is correct.
Step-by-step explanation:
The environmental costs associated with natural gas production include several key issues but not all the listed options actually apply. To clarify, trace metals released during combustion are primarily associated with the burning of coal, rather than natural gas. Gas combustion is relatively cleaner, with lower emissions of carbon dioxide, nitrogen oxides, and sulfur dioxide and does not produce ash or toxic emissions at the same level as coal or oil.
On the other hand, environmental costs that do apply to natural gas include the construction of pipelines through environmentally sensitive areas, methane release into the atmosphere during drilling and transportation, and land degradation due to drilling techniques such as fracking, which can contaminate groundwater.