Final answer:
The mystery food sample's color change to red upon contact with Sudan IV indicates the presence of lipids; no other macromolecules were detected as there were no reactions with Benedict's solution, Iodine solution, or Biuret solution.
Step-by-step explanation:
The mystery food sample contains a lipid because it was red in contact with the indicator Sudan IV, which is an indicator of lipids. The food sample was also tested with the following indicators: Benedict's solution, Iodine solution, and Biuret solution. No color change was present with the other indicators; therefore, the mystery food sample contains only lipids and no other macromolecules.