Answer:
b. 2050
Step-by-step explanation:
The ozone layer has been under heavy influence by the human activity during the past century, with the main reason being the releasing of certain chemicals into the atmosphere, which were destroying the ozone. The danger was noticed on time though, so quickly some measures were undertaken to save and return the ozone back to its natural state before it is too late. The measures were simple, stop the usage of certain chemicals and releasing them into the atmosphere. This quickly started to have a positive effect and the ozone layer has bee recovering well, and around 2050 it is expected that it will get back to its pre-1980 condition.