which does NOT have the same vowel saund

odd one out-in each group,find one word which does NOT have the same vowel saund as the other words.
1. A. gO B.dOctor C.pOster D.Old
2. A. cOme B.lOve C.Only D.frOnt
3. A.tOday B.shOp C.strOng D.Orange
4. A.cOmic B. nOt C. clOck D .Open
5. A.bOx B. clOse C.sOrry D.On