In this lab, you will figure out who was guilty of the classroom good mess by determining which macromolecules are present in the mystery food sample.

Rephrase this statement as a scientific question you can answer through investigation.

The correct answer to this question is this one:

The scientific question that you can answer through investigation is this:

Which macromolecules are present in the mystery food sample?

As an additional, here's the hypothesis that you can formulate:

If the mystery food is tofu, then it will react with the reagent that indicates the presence of a protein because tofu is primarily protein

The mystery food sample did not test positive for protein using the Biuret indicator, so the sample can not be tofu, which is what Zack ate.