Riley is testing how quickly sugar water freezes. he adds sugar water to one ice tray and plain water to another ice tray. he places each tray in the freezer and records the time when each one starts to freeze. what is the treatment in this experiment?

a.) water
b.) freezer
c.) ice tray
d.) sugar

The correct answer is option D.  

The treatment in this experiment is sugar. Plain water has a freezing point of 0°C. But sugar water (or water treated with sugar) has a lower freezing point than pure water. The treatment here sugar causes depression or lowering of the freezing point of water. Sugar is the solute and water is the solvent here.