Among the methods used to achieve paragraph coherence, which is considered the most complex?

The most complex method of achieving paragraph coherence is parallel structure. This technique involves using the same grammatical format for lists or sequences of ideas within a paragraph, which helps to create a rhythm and flow that enhances coherence. When a writer employs parallel structure, they align similar ideas or elements in a symmetrical way, making the connections between them clearer to the reader. This not only improves readability but also emphasizes the relationships among the components of the paragraph, allowing the reader to grasp the underlying logic more effectively.

On the other hand, transitional expressions serve as bridges between sentences and ideas, helping the reader to follow the thought process more easily. Pronouns link sentences to avoid repetition of nouns, contributing to coherence in a more straightforward manner. Repetition of key terms can reinforce main ideas but doesn't possess the depth of complexity found in parallel structure. By using parallel structure, writers engage their audience at a deeper level, showcasing the sophistication of their writing and the relationships among their ideas.