About 12,000 Years Ago,climatic Conditions Changed,resulting in New Forests,more Plant

About 12,000 years ago,climatic conditions changed,resulting in new forests,more plant food,and abundant sources of fish and other food around lakeshores,bays,and rivers.Human populations developed new techniques to catch and kill animals,and spent more time fishing and collecting wild plant foods.This new way of life marks the beginning of the Middle Stone Age,also called the:

A) Lower Paleolithic.
B) Middle Paleolithic.
C) Upper Paleolithic.
D) Mesolithic.
E) Neolithic.