Which macromolecules were present in the unknown solution? in the milk?

These macromolecules might either be amino acids, proteins or nucleic acids. They are accountable for the chemical changes and reactions that moves largely the cell and its composition. Take for example the cytoplasm of the cell where these organelles are settled. These simple organelles are composed of macromolecules which ignites and catalysis different functions that enables cells, in macro-perspective in motion and metabolism. In intestines for instance, metabolism occurs and breaking down parts of a food to simpler compounds that are used and these nutrients delivered throughout the body and again broken down by into smaller components. 

d. sodium chloride ions.

dogs is better and probably lizards.