Option 1 states that doorways and windows in Harappan settlements generally faced side lanes rather than main streets. This means that houses were designed in a way that promoted privacy and limited direct access to the main streets. This aligns with the characteristic features of Harappan settlements.

Option 2 mentions that houses in Harappan settlements generally had separate bathing areas and toilets. This indicates the presence of advanced sanitation systems, which were considered a characteristic feature of Harappan settlements.

Option 3, the correct answer, states that the citadel was walled but the lower town was not walled. This means that the fortified area or citadel, which is usually the highest point of the settlement, was protected by walls. However, the rest of the town, or the lower town, did not have surrounding walls. This is not in line with the characteristic features of Harappan settlements, as they typically had defensive walls around the entire settlement.

Option 4 suggests that drains and water chutes from the second storey were often built inside the walls of Harappan settlements. This indicates an advanced urban planning and sewage system, which was indeed a characteristic feature of Harappan settlements.

In summary, options 1, 2, and 4 describe characteristic