The sewer pipes A. Carry sewage as gravity conduits B. Are designed for generating self-cleansing velocities at different discharge C. Should resist the wear and tear caused due to abrasion D. All the above

The correct answer is D. All of the above.

Sewer pipes are designed to carry sewage as gravity conduits. They are also designed to generate self-cleansing velocities at different discharge rates. This means that the pipes are designed to allow the sewage to flow through them at a speed that is fast enough to prevent the build-up of solids. The pipes should also resist the wear and tear caused due to abrasion. This is because sewage is a corrosive substance that can damage the pipes over time.

Here is a brief explanation of each option:

• Option A: Carry sewage as gravity conduits. Sewer pipes are designed to carry sewage as gravity conduits. This means that the pipes are sloped in such a way that the sewage flows downhill. This is necessary in order to prevent the sewage from backing up.
• Option B: Are designed for generating self-cleansing velocities at different discharge rates. Sewer pipes are designed to generate self-cleansing velocities at different discharge rates. This means that the pipes are designed to allow the sewage to flow through them at a speed that is fast enough to prevent the build-up of solids. This is important because solids can clog the pipes and cause backups.
• Option C: Should resist the wear and tear caused due to abrasion. Sewer pipes should resist the wear and tear caused due to abrasion. This is because sewage is a corrosive substance that can damage the pipes over time. It is important to use pipes that are made from materials that are resistant to corrosion.

I hope this helps!