1. D. sister (The underlined part "ir" in "bird," "girl," and "first" has the same sound, while "sister" has a different sound.)
2. B. sun (The underlined part "u" in "burn," "hurt," and "turn" has the same sound, while "sun" has a different sound.)
3. B. picture (The underlined part "ur" in "nurse," "surf," and "return" has the same sound, while "picture" has a different sound.)
4. C. culture (The underlined part "ur" in "neighbor," "favorite," and "tourist" has the same sound, while "culture" has a different sound.)
5. B. hour (The underlined part "h" in "hobby," "hotel," and "hot" has the same sound, while "hour" has a different sound.)