Find the word which has a different sound

                                        The end 
đề số 4 A. USE OF ENGLISH:
I.Find the word which has a different sound. 
1 . A.then B. Them C .thing D. Their
2 A.ask B. Plastic C. back D.grandparent 
3 A . Start B . Marbles C. Stars D. Solar 
4 A.hear   B.clear C. Bear D. Fear 
5 A.cave B. Famous C. Late D. Channel