请找出每个小题中不属于同一类的选项，并将字母标号填写在题前括号内。
(   ) 1. A. Social Studies   B. homework   C. Moral Education     D. P. E.
(   ) 2. A. young            B. short      C. quiet              D. thin
(   ) 3. A. fruit            B. grape      C. apple              D. orange
(   ) 4. A. mountain         B. sky        C. air                D. healthy
(   ) 5. A. closet           B. path       C. mirror             D. end table