The answer is the first one (a): Vision.
Explanation for each option:
a. Vision: The medulla oblongata does not play a direct role in processing visual information. Vision is primarily processed by the occipital lobe of the brain and involves structures such as the retina and the visual cortex.
b. Balance: The medulla oblongata is involved in processing balance and equilibrium. It works with the vestibular system, which includes the inner ear and other parts of the brain, to help maintain balance and posture.
c. Hearing: The medulla oblongata is involved in the auditory pathway. It processes auditory information as it travels from the ear to the brain, playing a role in the initial stages of hearing.
d. Taste: The medulla oblongata is involved in processing taste. It receives signals from the taste buds and is part of the gustatory pathway.
In summary, the medulla oblongata is not involved in the processing of vision, making option (a) the correct answer.