Question

Jack wants to find out which laundry detergent cleans the best. so, he takes a cotton sheet and cuts it up into equal squares. He stains four squares with chocolate, and four with grape juice. He washes one of each of the squares in each of the 3 detergents. One from each set of squares is washed in water alone. For each wash load, he used: the same amount of water, the same amount of detergent and the same temperature and water.

What is the independent variable?, dependent variable, control, constant, hypothesis?