Answer : 1. "The colour red"
Explanation :

Harappan pottery 'Harappa' is an ancient site on the left bank of the Ravi River in Montgomery district, located in the Punjab province of Pakistan. Under the direction of John Marshall, in 1921, Dayaram Sahni started the excavation work of this site. In 1946, Martimer Wheeler excavated here to find out the form of rampart for the protection of the western fort mound of Harappa. Copper seals have been obtained from the excavation of Harappa city. The script of the language of this region was pictographic. Elephant, rhinoceros, tiger and bull are inscribed on the seal of Pashupati received from Mohenjodaro. Red color is commonly used on Harappan pottery.