Select the most appropriate option to fill in blank number 2.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. in.
The passage talks about the barrier "Ozone layer". The sentence talks about the presence of ozone in the atmosphere.
"In" is used to indicate something that exists or occurs within a certain area or volume.
So, the appropriate preposition for the filler is 'in'.