question: What has been lost that created a hole over the south pole?
choices.text: calcium gas ozone smoke water oxygen fluid erosion
choices.label: A B C D E F G H
fact2: An annual ozone hole over Antarctica has been observed since the 1980s.
combinedfact: Loss of ozone has created a hole over the south pole
formatted_question: What has been lost that created a hole over the south pole? (A) calcium (B) gas (C) ozone (D) smoke (E) water (F) oxygen (G) fluid (H) erosion