Cell nucleus chromosome gene nucleotide base subunit atom
The Cambrian Period marks an important point in the history of life on Earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion," because of the relatively short time over which this diversity of forms appears
The cerebrum controls the higher brain functions such as speech, writing, etc. The cerebellum deals with the involuntary stuff. The other 2 are nowhere near what you are looking for. B - Cerebrum is your answer.
