Introduction:
The Indus Valley Civilization, also known as the Harappan Civilization, was one of the oldest urban civilizations in the world, thriving around 2500 BCE to 1900 BCE in the region of present-day Pakistan and northwest India. It was characterized by well-planned cities, advanced architecture, and sophisticated urban infrastructure. However, one statement among the given options is incorrect. Let's explore each statement to identify the incorrect one.

Evidence of some form of irrigation has been found:
- The Indus Valley Civilization had a well-developed agricultural system, and evidence of irrigation has been discovered.
- The presence of canals, reservoirs, and wells suggests that the civilization practiced irrigation to support its agricultural activities.
- This allowed the civilization to cultivate crops and sustain a large population.

Embroidered garments were unknown in Indus civilization:
- This statement is incorrect. Embroidered garments were known in the Indus Valley Civilization.
- Archaeological excavations have revealed the presence of terracotta figurines wearing embroidered or patterned clothes.
- These figurines provide evidence of the existence of embroidery and textile arts in the civilization.

Many of the cities had covered drains:
- This statement is correct. Many cities of the Indus Valley Civilization had well-planned drainage systems.
- The cities were built with a grid-like pattern of streets, and each house had its own bathroom and a covered drain connected to the main sewage system.
- The drainage system indicates the advanced urban planning and sanitation practices of the civilization.

Mohenjodaro, Harappa, and Lothal had storehouses:
- This statement is correct. Mohenjodaro, Harappa, and Lothal, among other cities of the Indus Valley Civilization, had storehouses.
- Archaeological evidence, such as large granaries and storage jars, suggests that these cities had dedicated storage facilities.
- These storehouses were used to store surplus agricultural produce and goods, indicating a well-organized economic system.

Conclusion:
In conclusion, among the given statements, the incorrect one is option 'B' - "Embroidered garments were unknown in Indus civilization." This is incorrect as evidence of embroidered garments has been found in the Indus Valley Civilization through archaeological excavations. The civilization had a well-developed irrigation system, cities with covered drains, and storehouses for storage purposes.

• A stone statue of an important man found from Mohenjodaro shows him wearing an embroidered garment. This gives evidence about the use of embroidered garments.