Answer:
The inhabitants of Mohenjo Daro and Harappa dealt with wastewater and garbage by using advanced sewage systems and waste disposal methods12.
They had a sophisticated drainage system to dispose of waste materials out of town1. The waste water and other sewage of almost every house was channeled into the drain running along the street outside2.
Sewage was disposed of through underground drains built with precisely laid bricks, and a sophisticated water management system with numerous reservoirs was established1. In the drainage systems, drains from houses were connected to wider public drains laid along the main streets1.
The water from bathrooms on the roofs and upper stories was carried through enclosed terracotta pipes or open chutes that emptied into the street drains1.
So, the correct answer is: B) By using advanced sewage systems and waste disposal methods.