Piping and resistance to corrosion and low pH?

"which pipe is most susceptible to corrosion & low pH"

1. Reinforced concrete, because both cement and steel are susceptible to attack from acids.
2. Asbestos reinforced concrete, because the cement is susceptible to attack from acids but the asbestos is not.
3. Polymer pipes are generally corrosion and acid resistant; they are susceptible to attack by organic solvents.

The first two.