Step 1: Understanding the context.
The sentence describes a voice that captivated the audience, implying that the voice is pleasant and easy to listen to. We need to choose a word that describes such a voice.
Step 2: Analyzing the options.
(A) mellifluous: This word means sweet or musical, especially when describing a voice, and it fits the context of a voice that is pleasing to hear.
(B) sonorous: This word means a deep, rich, and full sound, which could be used to describe a voice but does not necessarily imply sweetness. It is not as fitting as "mellifluous" in this context.
(C) mellisonant: This is a rare word and not commonly used in this context. It is essentially a less common version of "mellifluous", but it’s not the best choice.
(D) dulcet: This word also means sweet, but it’s often used for music or sounds in general. While it could fit, "mellifluous" is a more common and precise term for a pleasing voice.
(E) melodious: This refers to something that has a pleasant melody, which could describe a voice, but it focuses more on the melody itself rather than the pleasantness of the voice.
Step 3: Conclusion.
The correct word is (A) mellifluous, as it specifically refers to a smooth, sweet, and pleasant sound, making it the best fit for describing the voice in the context of this sentence.