The archaeological findings of which grain are relatively rare at Harappan sites?

Rice

The correct answer is Option (1) → Rice

"The Harappans ate a wide range of plant and animal products, including fish. Archaeologists have been able to reconstruct dietary practices from finds of charred grains and seeds. These are studied by archaeo-botanists, who are specialists in ancient plant remains. Grains  found at Harappan sites include wheat, barley, lentil, chickpea and sesame. Millets are found from sites in Gujarat. Finds of rice are relatively rare."