Answer:
B. need to find fresh food and water sources
Explanation:
Nomadic groups rely on hunting and gathering activities in order to fulfill their basic needs. Often times, they find themselves in a situation when food or water sources in a certain area became depleted. (Can be caused by climate or overexploitation from the hunters/gatherer).
This is the reason why they became nomadic. When they can no longer find food source in their area they will move their whole group to another area and hunt/gather the foods there.
