The question asks for the word that is opposite in meaning to the underlined word, "Lucidity". The sentence provided is: "Lucidity is a desired quality in effective communication."
"Lucidity" refers to the quality of being clear, coherent, and easy to understand. In the context of communication, it means expressing ideas in a way that is readily comprehensible.
Based on the meanings, "Ambiguity" is the most suitable opposite for "Lucidity". While lucidity implies clear and single meaning, ambiguity implies unclear or multiple meanings.