Which of the following is an example of a homogeneous mixture?

A homogeneous mixture is defined as a mixture that has a uniform composition throughout, meaning that the different components are indistinguishable from one another at the macroscopic level. In the case of salt water, when table salt (sodium chloride) is dissolved in water, it forms a solution where the salt ions are evenly distributed throughout the water. This uniformity means that if you take a sample of the salt water from any part of the solution, it will have the same composition as any other sample.

In contrast, the other choices represent mixtures that are not homogeneous. For instance, sand and salt are a heterogeneous mixture because the individual granules of sand and salt can be seen and separated. Oil and water do not mix uniformly, leading to distinct layers, while granite is a solid rock composed of different minerals that can be visually identified as separate components. These examples highlight the key distinction between homogeneous and heterogeneous mixtures, underlining why salt water is the correct choice as a homogeneous mixture.