The correct answer is "sewer systems (bathrooms with toilets)."
The correct answer is "sewer systems (bathrooms with toilets)." The Indus Valley civilization had an advanced and well-organized system of sewerage and drainage, with bathrooms equipped with toilets. This was a unique feature that no other civilization had before. To determine the correct answer, you can analyze the descriptions provided for each option and compare them to historical knowledge. In this case, knowing about the advanced urban planning of the Indus Valley civilization would lead you to choose the option mentioning sewer systems.
