Answer the following question given this paragraph: 

Ozone near the ground harms human health. Ground-level ozone is a pollutant. But the ozone layer in the stratosphere protects us from harmful solar rays. That’s why people were alarmed in the 1980s to learn that there was a hole in the ozone layer.


Q: When did we learn there was a hole in the ozone layer?

 Choices:

- 1950s

- 1970s

- 1990's

- 1980s

A:
1980s
