The world is going through the worst pandemic in the past hundred years. The air travel industry is facing a crisis, as the resulting quarantine requirement for travelers led to weak demand. In relation to the first sentence above, what does the second sentence do?

The correct option is: States an effect of the first sentence.

To understand the relationship between the two sentences, we can analyze the cause-and-effect link between them:
1. The Cause (First Sentence): "The world is going through the worst pandemic in the past hundred years." This sentence establishes the primary event or circumstance: a severe global health crisis.
2. The Effect (Second Sentence): "The air travel industry is facing a crisis, as the resulting quarantine requirement for travelers led to weak demand." This sentence describes a direct consequence of that pandemic. The use of the word "resulting" indicates that the quarantine requirements and the subsequent economic downturn in the aviation sector are direct outcomes of the global pandemic described in the first sentence.

Therefore, the second sentence functions to show the impact or effect of the situation introduced by the first sentence.