The answers to your question would be C and D. A mixture is either homogenous, meaning it is completely uniform throughout, an example being salt water, and heterogeneous, meaning a solution has larger sized particles that can interact with each other, an example of this being an Italian salad dressing. You can always tell by removing a part of the solution, if both the removed part and the original are exactly the same, then it is homogenous. I hope this helps!