Question

read the passage again.anesthetics were used to stop severed nerves from sending atypical signals to patients brains. after receiving the anesthetic, some patients reported that their phantom pain went away. however, other patients continued to feel pain.these results show that damage to the peripheral nervous system cannot be the only factor causing phantom pain. atypical signals from the peripheral nerves appear to contribute to phantom pain. yet changes to the central nervous system are also likely factors in phantom pain experienced by at least some patients.consider the conclusion:both the peripheral nervous system and the central nervous system likely contribute to phantom pain.what information supports the conclusion that the central nervous system likely helps produce phantom pain?phantom pain disappears only when anesthetics are applied to parts of the central nervous system in addition to peripheral nerves.signals from severed peripheral nerves are not much different from typical nerve signals. so, these signals are not able to cause phantom pain on their own.for some patients, phantom pain does not stop after peripheral nerve signals are blocked. so, other parts of the nervous system likely contribute to phantom pain.

Explanation:

The question asks for evidence that the central nervous system contributes to phantom pain. The key is identifying that blocking peripheral nerve signals (via anesthetics) did not stop phantom pain in some patients, which points to another part of the nervous system (the central nervous system) being involved. The other options either focus on needing both systems or dismiss peripheral signals entirely, which does not match the passage's logic.

Answer:

For some patients, phantom pain does not stop after peripheral nerve signals are blocked. So, other parts of the nervous system likely contribute to phantom pain.