Polyvinyl chloride, or pvc, is used in most water-carrying pipes in the united states. known for their resistance to the corrosion that can be caused by water, pvc pipes are more durable than the metal pipes of old. as useful as pvc is, it may be surprising that it was accidentally discovered in 1835 by henri victor regnault, who observed a mysterious white solid plastic forming inside some test tubes that were left exposed to sunlight in his lab.
it can be inferred from the passage that metal pipes:

a. are used more than pvc pipes outside of the united states
b. are more expensive than pvc pipes
c. are more likely to corrode than pvc pipes
d. are no longer used in the united states