The structural beams of an offshore drilling rig are made of steel and are partially submerged in sea water. The submerged portions are observed to corrode, and your engineering assignment is to decrease the corrosion rate of the steel by putting a second metal in contact with the beams. For each of the following arrangements, indicate whether it will decrease the corrosion of the steel beams, and explain your answer.
a. Zinc placed above the water line (not submerged)
b. Tin placed below the water line (submerged)
c. Lead placed below the water line (submerged)
d. Nickel placed above the water line (not submerged)
e. Magnesium placed below the water line (submerged)