Respuesta :
Carbon Dioxide
Nitrous Oxide
In 2014, nitrous oxide (N2O) accounted for about 6 percent of all U.S. greenhouse gas emissions from human activities. Nitrous oxide is naturally present in the atmosphere as part of the Earth's nitrogen cycle, and has a variety of natural sources.
(SOURCE: https://19january2017snapshot.epa.gov/ghgemissions/overview-greenhouse-gases_.html0)