Terracotta models of the plough have indeed been discovered at the Harappan site of Banawali. These terracotta artifacts provide archaeological evidence of agricultural practices and tools used by the Harappan civilization, such as ploughs. Banawali is one of the many Harappan sites where such artifacts have been excavated, shedding light on the agricultural practices and tools of this ancient civilization.

So, the correct option is [3].