Which of these is an example of a physical change? A. sugar dissolving in warm waterB. iron rusting in the presence of moist airC. wood burning in the presence of oxygenD. baking soda reacting with acid to form a gas

The answer is A) sugar dissolving in warm water

Explanation:

That's the only example where the composition of the molecules does not change.

The sugar scatters among the water molecules but they are still sugar molecules.

In all the other cases there are chemical reactions that change the molecular structure of the materials you started with.