3. The graph below, adapted from your textbook, shows the concentrations of various metals in the sulfide-rich primitive oceans compared to our modern-day ocean. a) For each element below, indicate whether its concentration increased, decreased, or stayed the same over time. Magnesium: Iron: Copper: b) Using your knowledge of chemistry, reduction/oxidation, and solubility rules, provide a chemical explanation for the cause of the differences you indicated for each element below: Magnesium: Iron: Copper