S has many oxidation states including -2,0,2,4,6...
in this particular reaction the oxidation state of S is "+2"
a decrease in oxidation state - reduction
an increase in oxidation state - oxidation
1.) S + O2 -> SO2
here at the left handside, as sulphur exists itself (not compound), the oxidation state is 0
at the right hand sidde it forms a compound and gains an oxidation state of +2 = this is oxidation
whereas O has an oxidation state of "0" in the left hand side and decreases to -4 in the right hand side
this is reduction
therefore its redox
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2.) the sulphur gains oxygen atoms (oxidation) and the oxidation state of oxygen reduces..(reduction)
therefore it is redox
so the answer is "C"
1 and 2