Read the scenario and examine the table.
Ivan wants to test how the amount of water consumed each day affects the number of facial blemishes people receive over a month. He gathers 12 people and divides them into 3 groups. He keeps everything the same for each group except for daily water and food intake. Throughout the month, Ivan tallies the number of facial blemishes each individual receives. The table details how Ivan changed the independent variables for each group.
Note: Group 1 is Ivan's control group.
What error did Ivan make in the design of his investigation?
A.) Ivan did not record the results for the dependent variable in a data table.
B.) Ivan did not determine the average number of blemishes received.
C.) Ivan tested more than one independent variable at a time.
D.) Ivan had the individuals in the control group consume water.