1. The Puritans considered buttons a (sign) of vanity. - C. object complement (the object is buttons, and the word sign completes it)
2. At first the old trunk in the basement appeared (empty). - E. predicate adjective (the first adjective after the linking verb appeared)
3. Michelle showed (Mom) a copy of the yearbook. - B. indirect object (Mom is indirect, and a copy of the yearbook is direct)
4. Kim named her (dog) Trixie. - A. direct object (named whom?)
5. The performance was a huge (disappointment). - D. predicate nominative (the first noun after the linking verb was)