The correct answer is D. All the above.
Asbestos cement sewers are made of a mixture of asbestos fibers and cement. Asbestos is a naturally occurring mineral that is resistant to heat, fire, and corrosion. Cement is a binding agent that holds the asbestos fibers together.
Asbestos cement sewers are light in weight and easy to install. They are also resistant to corrosion by acids and other chemicals. However, asbestos cement sewers are not structurally strong to bear large compressive stress. They can be damaged by heavy loads or by being crushed by falling objects.
Asbestos cement sewers are also susceptible to corrosion by sulphuric acid. Sulphuric acid is a common industrial chemical that can be found in wastewater. When sulphuric acid comes into contact with asbestos cement, it can cause the material to break down and crumble.
For these reasons, asbestos cement sewers are no longer manufactured or installed in the United States. They have been replaced by more durable and safer materials, such as PVC and polyethylene.