what can the reader infer from this passage?
a.
the brain stem is in the middle of the human brain.
b.
the brain stem is crucial to life for human beings.
c.
the brain stem provides blood to the whole brain.
d.
the arteries of the brain stem are often blocked.
story: the brain is a large and extremely complex organ. different parts of the brain perform different functions. scientists believe that different parts of the brain developed at different points in human history. one important section of the brain, the brain stem, controls some of the body's most important functions. for instance, the brain stem controls breathing, heart rate, swallowing, and some aspects of speech. because the brain stem is in charge of such important functions, scientists think it was one of the first parts of the brain to evolve. the brain stem is located at the base of the brain, at the top of the spinal cord. it is made up of three parts: the midbrain, the pons, and the medulla. six different arteries bring blood to the brain stem. if any of these arteries becomes blocked, a stroke or other life-threatening problem is possible.