Answer:
C. Without mitigation, the conference deteriorated into a full-fledged hullabaloo.
Explanation:
The answer is "C" because in the sentence <em>"Without mitigation, the conference deteriorated into a full-fledged hullabaloo" </em>there is a use of formal words such as mitigation, deteriorated, full-fledged hullabaloo. We can say the same with other words using an informal language:
<em>"The conference was a complete disaster."</em>
You can use informal language when you are talking to your family or friends but you can't use informal language when you are writing an essay.