Which logical fallacy is characterized by convoluted language that obscures the argument?

The logical fallacy characterized by convoluted language that obscures the argument is best identified as ambiguity. Ambiguity arises when language or expressions can be interpreted in multiple ways, creating confusion and making it difficult for the audience to grasp the intended message. This vagueness can cloud the argument, leading to misunderstandings regarding the issue being debated.

The other options highlight different types of logical fallacies. Circular reasoning occurs when an argument's conclusion is used as its premise without providing additional support. A complex question involves framing a question in such a way that it assumes something not established as true, leading the respondent into a trap. A red herring is an irrelevant point introduced to divert attention from the main issue. While these represent different pitfalls in reasoning, ambiguity specifically pertains to the use of unclear or convoluted language that hampers clear argumentation.