The correct answer is B. A thicker cerebral cortex
Step-by-step explanation:
The cerebral cortex is a layer found in the cerebrum, and therefore in the brain of mammals including elephants, humans, and rats. This section of the brain integrates multiple neural connections, and it is related to several aspects such as memory, language, attention or intelligence.
In the case of rats, scientists found a rich environment leads to a thicker cerebral cortex. This occurs because a rich environment leads to the formation of more complex neural connections, which is related to attention and intelligence levels. Besides this, the time rats were exposed to an enriched environment affect this development as short exposition does not lead to a thicker cerebral cortex, although it can improve aspects such as attention. Therefore if a rat is raised in an enriched environment it develops a thicker cerebral cortex.