Here are the best answers for each question:

11. **A. deadline** (The underlined part "dead" is pronounced differently from the others.)
12. **C. metro** (The primary stress pattern differs as it is in the second syllable.)
13. **A. a** (This "a" is pronounced differently from the others as a standalone word.)
14. **A. in** (It’s used correctly with the preposition "in" which does not change.)
15. **C. biggest** (The superlative form has a different grammatical structure.)
16. **C. If** (It correctly introduces a conditional clause.)
17. **B. Because** (This provides a reason in conversation.)

Feel free to ask if you need more help!