Question: The recent rise in atmospheric CO2: Group of answer choices Was caused primarily by a combination of increased volcanic activity and by oceanic outgassing, as shown by the news about volcanoes and the loss of CO2 from the ocean Was caused by hot air from politicians giving talks about global warming Was caused primarily by human fossil-fuel burning, as shown by the match between the amount burned and the rising atmospheric and oceanic concentration, the lack of notable change in volcanism, and by atmospheric tracers that identify fossil-fuel CO2 Might have been caused by human burning of fossil fuel, or by increased volcanic action, or by outgassing of the ocean; there is really no way to tell these apart Was caused primarily by increased volcanic activity, as shown by the large number of volcanoes in the news in recent years