We now know that the warming of the earth in the last 200 years is largely due to humans and their effects on:

atmospheric carbon dioxide
organochlorides
environmental pollutants like arsenic
biomagnified mercury
none of the answer choices are correct.

atmospheric carbon dioxide

Explanation:

Carbon dioxide is a greenhouse gas, meaning that it absorbs heat and releases it slowly over time. Carbon dioxide concentrations are increasing due to the fossil combustibles that society is using to create energy. The constant rise of greenhouse gases in the last 200 years has caused the Earth's energy balance to become unstable, absorbing extra heat and increasing Earth's temperature.

Hello,

The two most densely populated continents (Not countries) in the world are,

1 - Asia

2 - Europe

- I.A. -