The products of ozonolysis of 1,2-dimethyl benzene (o-xylene) are:

1. Methylglyoxal, 1, 2-dimethylglyoxal, and glyoxal

2. Methylglyoxal, 1, 3-dimethylglyoxal, and glyoxal

3. Methylglyoxal, 1, 4-dimethylglyoxal, and glyoxal

4. Methylglyoxal, 1, 5-dimethylglyoxal, and glyoxal