Comparing gas bubbles within layers of antarctic ice show that fossil fuel use has raised the amount of in the air to the highest levels in human history. a. carbon dioxide b. greenhouse gas c. lead d. mercury

According to the united nations refugee agency, more than 2/3 of the world's refugees come from just five countries. which country is not on that list? a) turkey b) myanmar c) afghanistan d) south sudan

Which of the layers of the earth has the following three characteristics? i. it is made of molten rock. ii. it has currents that are constantly moving. iii. earth’s plates float on top of its currents.

Which of the following statements best characterizes changes to agriculture in the united states since 1900? a. increased mechanization has reduced the need for labor.b. increased mechanization has increased the need for water, thereby increasing the need for labor.increased mechanization has increased the use of land, thereby increasing the need for labor.d. increased mechanization has increased food production, thereby increasing the need for labor. select the best answer from the choices provided.