<span>During photosynthesis, plants use carbon dioxide and produce oxygen. During metabolism oxygen is used and carbon dioxide is a product. Humans impact the carbon cycle during the combustion of any type of fossil fuel, which may include oil, coal, or natural gas.</span>
The most appropriate unit for describing a 26 mile marathon run would be C. Kilometre. As kilometres can be easily utilized and converted to miles and vice-versa.
<span>a)Stem cells must always be provided by a donor who is financially compensated.</span>
