Circle the word which has the underlined part is pronounced differently from others

Circle the word which has the underlined part is pronounced differently from others. 
1. allergy       b. Atomosphyrus C. Teenager d. Calorie
2.a.guess      b. Big       C. Sign     D. Again
3.a.fear         b. Earn       C. Hear     D. Clear
4.a.community     b. Happy     C. itchy    D. By