Answer: D. Enrique’s dream is to become a full-time singer.
Only option D uses the hyphen correctly. In the other options, the words there do not need hyphens. In option A, two adjectives can be hyphenated but not after a noun. In other words, the phrase “well-behaved little sister” is correct unlike “my little sister was well-behaved” which is not allowed in the rules of the English language.