Question

How have human activities changed Earth's atmosphere over the past 200 years?

A. They have increased the levels of greenhouse gases.
B. They have reduced the level of nitrogen gas.
C. They have increased the level oxygen gas.
D. They have reduced the levels of greenhouse gases.

Answer 1

100% A

Explanation: cuz im doing the text rn

Answer 2

Answer: A

Step-by-step explanation:

Because I did this before