Heterogeneous Mixture
Heterogeneous mixtures are those mixtures in which the components are not uniformly distributed throughout the mixture. Let's analyze the options given to determine which one is a heterogeneous mixture.

A) 24 Carat Gold
- 24 carat gold is a pure substance, not a mixture. It consists of only one type of atom, which is gold. Therefore, it is a homogeneous substance, not a heterogeneous mixture.

B) Rectified Spirit
- Rectified spirit is a homogeneous mixture of ethanol and water. It is a clear liquid where the components are uniformly distributed at a molecular level. Therefore, it is not a heterogeneous mixture.

C) Gasoline
- Gasoline is a mixture of various hydrocarbons such as octane, heptane, and others. These components do not mix uniformly and can separate into different layers based on their densities. Therefore, gasoline is a heterogeneous mixture.

D) Iodized Table Salt
- Iodized table salt is a homogeneous mixture of sodium chloride (salt) and potassium iodide. The components in iodized salt are uniformly distributed throughout the mixture. Therefore, it is not a heterogeneous mixture.

Conclusion
Based on the analysis, the heterogeneous mixture among the options given is C) Gasoline . Gasoline consists of different components that do not mix uniformly, leading to the formation of distinct layers, making it a heterogeneous mixture.