The correct answer is option 3, which states that the burning of fuel and rusting of iron represent a chemical change.

Let`s analyze each option to gain a better understanding:

1. Magnetization of iron: This is a physical change, not a chemical change. In magnetization, the arrangement of particles within the iron changes, but the chemical composition of the iron remains the same.

2. Condensation of liquid: This is also a physical change. When a gas or vapor cools down and turns into a liquid, the chemical composition of the substance remains unchanged.

3. Burning of fuel: This is a chemical change. Burning fuel involves the combustion process, where the fuel reacts with oxygen to produce heat, light, and various byproducts. The original chemical composition of the fuel is altered, resulting in the formation of new substances.

4. Rusting of iron: This is another example of a chemical change. When iron reacts with oxygen and water in the presence of air, it forms iron oxide or rust. This process involves the alteration of the chemical composition of iron.

In conclusion, options 3 and 4 correctly represent chemical changes, while options 1 and 2 involve physical changes.