Which three statements best describe the Harappan civilization? Three story brick homes c. an understood writing system
b. Sanitation and sewer systems d. Grid patterned streets

an understood writing system

Explanation: they developed the first accurate system of standardized weights and measures, some as accurate as to 1.6 mm.

i am pretty sure the awsers is d.

herodotus taught this. herodotus was an ancient greek historian who was born in halicarnassus in the persian empire. he is known for having written the book the histories, a detailed record of his "inquiry" on the origins of the greco-persian wars.