Circle the word whose underlined part is pronounced differently from the others

Circle the word whose underlined part is pronounced differently from the others’.
1.A. backache    B. channel  C. children
2.A. thirsty  B. surf  C. allergy
Exercise 2: Circle the word which has a different stress pattern from that of the others’.
3.A. allergy  B. volunteer  C. energy
4.A. collect  B. donate  C. cycle