A student wanted to test the effects of adding nitrogen to soil on plant growth. He adds different amounts of nitrogen to the soil of three identical plants. He does this for three weeks. The results are shown. Amount of Nitrogen Added (mL)Plant Growth (cm)amount of nitrogen added. plant growth0 mL 1 cm5 mL 1.2 cm10 mL 2.4 cm15 mL 3.6 cm20 mL 4.8 cm1. Which graph is the best choice for summarizing the data results? (line/bar?)2. What is the independent variable?3. What is the dependent variable?