The Greenhouse Effect Is a Natural Phenomenon That Keeps the Earth's

The greenhouse effect is a natural phenomenon that keeps the earth's surface warm.Without greenhouse gases-water vapor,carbon dioxide,methane,nitrous oxide,halocarbons,and ozone-life as we know it wouldn't exist.The current problem is that

A) most scientists dispute the anthropogenic reasoning for high concentrations of greenhouse gases.
B) the atmospheric concentration of greenhouse gases has reached its highest level in 400,000 years and will continue to rise, as will global temperatures, without actions to slow it down.
C) scientists cannot agree on a general model of how the greenhouse effect went from being a positive to a negative and a life-threatening force.
D) global warming actually benefits 90 percent of the world's population, so it is difficult to mobilize the will to address the anthropogenic causes of climate change.
E) it is difficult to distinguish between climate change and global warming.