The correct option is D Drains and water chutes from the second storey were often built inside the wall
Harappan civilsation, the earliest phase of urbanisation in the Indian subcontinent is renowned for town planning. Most of the cities were divided into two separate areas, the citadel, and the lower town. The citadel was mostly walled but the lower town was not walled. Moreover, houses were built around a rectangular courtyard, with doorways and windows generally facing the side lanes. The drainage system was well organised. Water flowed from houses to streets, where there were drains. Many a times, they were covered with bricks as well. Harappan towns are not known for having drains built inside walls of houses. Harappans were hygiene lovers and generally had separate bathing and toilet areas in their houses.