Step 1: Concept
The brainstem connects the brain to the spinal cord.
Step 2: Meaning
The medulla oblongata is the lowest part of the brainstem.
Step 3: Analysis
The medulla contains vital centers for heart rate and breathing and continues downward through the foramen magnum to become the spinal cord.
Step 4: Conclusion
Hence, the medulla extends to form the spinal cord.
Final Answer:(A)