Read what you've been given...... If there's protein, then the solution turns PURPLE. The answer is right there with statement #3. To quote: 3. If the solution turns purple, the food contains protein.
In the written directions the indicator that the matter contains protein is when the solution turns a purple color. Therefore we can conclude that if your sample causes the solution of Copper Sulfate and Sodium Hydroxide to turn purple, it does indeed contain protein.
