The indus valley are believed to have been settled:

after farms failed elsewhere and farmers migrated to the valley
when the river flooded its banks and left fertile silt in which to farm
when crops such as millet were found along the banks
when the people began worshipping multiple gods

The correct answer is when crops such as millet were found along the banks

The largest cities in the Indus Valley civilization were Harapa and Mohenjo-Daro. They were in present-day Pakistan. Harapa may have had 35,000 inhabitants and Mohenjo-Daro was even larger. There were also at least sixty smaller villages on the banks of the Indus River and the Oman Sea.

the number of senators, and representatives, the state has in congress.