Which of the following on reductive ozonolysis give only glyoxal?

Which of the following on reductive ozonolysis will give only glyoxal?

How many of the following on reductive ozonolysis will give only glyoxal? Ethylene, acetylene, 1,3-butadiene, benzene, o-xylene, m-xylene, p-xylene, cyclobutadiene, cyclooctatetrene.

Which of the folllowing on reductive ozonolysis will give only glyoxal?

o-xylene on reductive ozonolysis gives