As you ascend from the medulla oblongata to the cerebrum, the functions of each successive level becomeA) more complex. B) simpler. C) better understood. D) more crucial to visceral functions. E) critical to reflexes

The correct answer will be option A-more complex.

Explanation:

The brain is divided into three parts: cerebrum, cerebellum and Brainstem.

The medulla oblongata is a part of the brainstem which is involved in the response of the autonomic nervous system (ANS) like body temperature, breathing, digestion, heart rate, wake and sleep cycles, vomiting, sneezing, coughing and swallowing.

The cerebrum is the largest part of the brain which includes basal ganglia, hippocampus and olfactory bulb. This is involved in performing the higher functions of the central nervous system (CNS) like vision and hearing, speech, emotions, reasoning, learning and fine control of movement.

As we move from the medulla oblongata to cerebrum the response to stimuli changes from simple to complex as medulla oblongata is involved in simple processes of ANS whereas cerebrum is involved in the higher process of CNS like learning, speech and many more.

Thus, option A-more complex is the correct answer.