Inference 1 is Correct: The wide occurrence of spindle-whorls in Harappan households indicates that spinning was a common domestic activity. The absence of the spinning wheel (which was introduced to India much later during the medieval period) meant that Harappans relied on hand-spinning using drop spindles, which is a highly manual and laborious process.

Inference 2 is Correct: The discovery of highly standardized cubical chert weights and graduated measurement scales (such as the ivory scale at Lothal and shell scale at Mohenjo-Daro) reflects the advanced mathematical, metrological, and scientific knowledge possessed by the Harappans for trade, architecture, and construction.

Inference 3 is Incorrect: The presence of distinct, self-contained houses built with baked bricks, featuring their own private wells, bathing platforms, and large rooms, points toward a private property system and social stratification. A common property system would instead be characterized by shared, communal living spaces and collective ownership of resources.

Therefore, option A is the correct answer.