A student wants to investigate how adding fertilizer affects the growth of flowering plants. She gathers 10 identical flowering plants and divides them into two groups of five plants. One group receives the same amount of fertilizer at the same time each day for four weeks. The other group does not receive fertilizer. All plants in both groups are kept at the same temperature and given the same amount of water and light every day for four weeks. The growth of the plants after four weeks what would be the independent variable , dependent variable, hypothesis, and 3 controls