He placed the following into separate beakers of water (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip (c)1 iron nail wrapped with a magnesium strip (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water. what is the dependent variable