Read the passage and answer the questions:
The most ancient system yet discovered

About the drains, Mackay noted: “It is certainly the most complete ancient system as yet discovered.” Every house was connected to the street drains. The main channels were made of bricks set in mortar and were covered with loose bricks that could be removed for cleaning. In some cases, limestone was used for the covers. House drains first emptied into a sump or cesspit into which solid matter settled while wastewater flowed out into the street drain. Very long drainage channels were provided at intervals with sumps for cleaning. It is a wonder of archaeology that “little heaps of materials, mostly sand, have frequently been found lying alongside drainage channels, which shows... that the debris was not always carted way when the drain was cleared”. Drainage systems were not unique to the larger cities but were found in smaller settlements as well, At lothal for example, while houses were built of mud bricks, drains were made of burnt bricks.

The most unique feature of Harappan Civilisation was the development of:
(1) Craft centres
(2) Port centres
(3) Urban centres
(4) Rural centres

3

The correct answer is Option 3 - 3 (Urban centres)

The Harappan Civilization, also known as the Indus Valley Civilization, is renowned for its well-planned and sophisticated urban centres, making option (3) "Urban centres" the correct choice.

Perhaps the most unique feature of the Harappan civilisation was the development of urban centres. One such centre was Mohenjodaro. Although Mohenjodaro is the most well-known site, the first site to be discovered was Harappa.