None of the choices are correct
        
             
        
        
        
The medulla has the ascending and the descending tract which function to link the brain with the spinal cord.
<h3>What is the role of medulla?</h3>
- Medulla oblongata is the lowermost part of the brain.
- It is located at the place where the brain and the spinal cord connect thus it carries nerve signals between the brain to spinal cord thus help the entire body to communicate.
- It controls biological processes like blood pressure, breathing and heartbeat.
- Ascending tract functions to carry sensory information from the body (e.g.: pain) from the spinal cord to the brain (upwards). 
- Descending tract carry motor information (e.g.: instructions to move the arm) from the brain down the spinal cord to the body (downward).
- Damage to medulla can lead to respiratory failure, paralysis, or loss of sensation.
Learn more about medulla here:
brainly.com/question/26723889
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Answer:
enzymes are involved in DNA replication except Helicase.
 
        
             
        
        
        
It should be an igneous rock because it formed by the volcanoes lava cooling down