Buta-1, 3-diene on heating with maleic anhydride would give A. B. C. D.

In the case of buta-1,3-diene and maleic anhydride, the diene is the buta-1,3-diene and the dienophile is the maleic anhydride. The reaction between these two molecules would form a six-membered ring with two double bonds, 1,2-dimethylenecyclohexane-1,4-dione.

The Diels-Alder reaction is a very important reaction in organic chemistry. It is used to synthesize a variety of compounds, including pharmaceuticals, polymers, and dyes.

The other options are incorrect because they do not represent the products of the Diels-Alder reaction between buta-1,3-diene and maleic anhydride.