A student performed experiments to study how enzyme concentration affects the rate of hydrolysis (break down) of protein in milk. After the enzyme and milk were combined, the protein was hydrolysed and the mixture went from cloudy to clear. The student used five different enzyme concentrations and measured the time needed to reach the end-point for each one. What would be an appropriate control for this investigation?
- ACarrying out a further experiment where the enzyme solution is replaced with water.
- BCarrying out each experiment in a thermostatically regulated water-bath at $35^\circ\text{C}$.
- CPerforming three repeat experiments for each of the five enzyme concentrations.
- DUsing the same volume of enzyme solution for each of the five experiments.