The Indus, Ganges, and Brahmaputra were

important to ancient India because they were

(1) high mountain ranges that protected India

from invasion

(2) great rivers that flowed through India's fertile

northern plain

(3) Aryan gods to whom the priests prayed for

rain

(4) ruling dynasties that united the people of

Harappa and Mohenjo-Daro

The correct answer is - (2) great rivers that flowed through India's fertile northern plain.

Indus, Ganges, and Brahmaputra were and still are great rivers that run through the northern fertile plains of India. These three rivers have been the basis for sustaining large populations for thousands of years and give opportunity for the development of the civilizations on the Indian subcontinent. These rivers were creating fertile plains with alluvial soil around their banks from their annual floodings, the constantly fertile renewed soil gave the people the needed basis for producing huge amounts of food and thus manage to sustain themselves and also for trade, as well as allowing the building large vibrant cities and villages. Also their waters have been used for irrigation throughout the dry period of the year. Nowadays, unfortunately, all three rivers are heavily polluted and in desperate condition.