Which of the following alkenes give propanone as one of the organic products on ozonolysis followed by reductive work-up ($ceZn/H2O$)? Select all that apply.

Propanone arises from any alkene carbon that carries two methyl groups: $(\mathrm{CH}{}_3){}_2\mathrm{C}=$. 2,3-Dimethylbut-2-ene gives two propanone, 2-methylbut-2-ene gives propanone plus ethanal, and 2-methylprop-1-ene gives propanone plus methanal. 3,3-Dimethylbut-1-ene gives 2,2-dimethylpropanal plus methanal, with no propanone.