Final answer:
option a. Joanne would likely lose the ability to understand language after having her entire left hemisphere removed due to its role in language processing but might retain the ability to understand music if her right hemisphere, which is also involved with music processing, remains intact.
Step-by-step explanation:
Following the removal of her entire left hemisphere to treat severe epilepsy, Joanne would most likely no longer be able to understand language. This is because the left hemisphere is typically responsible for language processing. However, depending on which specific brain structures were affected and the extent of her brain's plasticity, her ability to understand music, which can also involve the right hemisphere, might remain intact, making option C the most likely answer.
Studies and cases involving individuals who have had a hemispherectomy or split-brain surgery reveal complex results. While certain functions primarily localized in one hemisphere may be lost, the brain often exhibits a remarkable degree of redundancy and plasticity, especially in children.
It's important to note that each case can be different based on a variety of factors including age at the time of surgery, the nature of the condition being treated, and individual variances in brain organization.