Answer: Option (d) is the correct answer.
Step-by-step explanation:
A solution is defined as a substance in which two or more substances are mixed together in such a way that their particles are evenly distributed throughout the mixture then it is known as a solution.
Components of a solution never combine chemically to each other. And, a solution is a clear in nature.
A solution in which solute particles are evenly distributed in a solvent is known as a homogeneous mixture.
For example, a mixture of salt in water is a homogeneous mixture.
On the other hand, a solution in which solute particles are unevenly distributed in a solvent is known as a heterogeneous solution.
For example, a bucket with salt water and sand is a heterogeneous solution.
Thus, we can conclude that a child fills a bucket with salt water and sand then contents of the bucket are classified as a heterogeneous mixture.