Answer:
A. to feed entire groups of people from relatively small numbers of food-sources
Step-by-step explanation:
With the modification in the plant cultivation and animal husbandry techniques, it is now possible grow and produce more food in less time period that allows to feed more people from relatively small numbers of food-sources.
Plant cultivation and animal husbandry techniques improves the quality and quantity of food for people having small number of food-sources
Hence, the correct option is "A".