The correct option is B
They believed in natural worship.
Explanation:
Option (a) is incorrect: Pictographic script was used in Indus valley Civilization.
Option (b) is correct: Belief system- Pashupati Seal, Pipal Tree, Humped Bull, Snake, Composite animals worship indicates natural worship.
Option (c) is incorrect: Lothal was a port city, but Mohenjodaro wasn’t.
Option (d) is incorrect: Trade was extensive internally and externally. Use of words like meluha, Dilmun are found in mesopotamian texts. Also, we can see many urban centres were developed during the Harappan age.