Animal studies show that manipulations that suppress neurogenesis lead to

Animal studies display that operations that overpower neurogenesis lead to memory impairments on many types of learning responsibilities and that condition that upsurge neurogenesis tends to be linked with enhanced learning on many tasks. In addition, neurogenesis may provide the brain with a supply of neurons that may vary in age and these differences may somehow let the brain to timestamp some memories of neurons that may vary in age and these differences may somehow let the brain to timestamp some memories. 

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.