Sara and Juan conducted an experiment to test which soil would be BEST for growing plants. They planted bean seeds in four pots and placed the pots in the sunlight. Each pot had a different type of soil. They used all three types of soil seen in the jar: sand, silt, and clay. They also made a mixture of soil using equal parts of sand, silt, and clay. Once the seeds were planted, they watered the pots every day and tracked the seed germination and plant growth.

What was the dependent variable in the experiment?