Pick up the incorrect size of stone ware sewers

Stoneware sewers are pipes made of vitrified clay, commonly used for wastewater and domestic drainage systems. They are known for their resistance to corrosion, smooth internal surface, and durability in handling sewage flow.

These pipes are manufactured in a range of standard internal diameters as per IS: 651 and other relevant specifications. The usual sizes range from 10 cm to 90 cm in internal diameter, making all the given options valid standard sizes.

Option A (52.5 cm) – Standard size.

Option B (67.5 cm) – Standard size.

Option C (82.5 cm) – Also a standard size, as large-diameter stoneware sewers are available up to 90 cm.

Since all the given sizes (52.5 cm, 67.5 cm, and 82.5 cm) fall within the standard manufacturing range of stoneware sewer pipes, none of them is incorrect.

Therefore, the correct answer is Option D: None of these.