What is a typical characteristic of under-processed hair following a perm?

Under-processed hair following a perm often exhibits characteristics that lead to it appearing limp and lacking volume. This occurs because the hair did not undergo sufficient chemical processing to achieve the desired curl formation. Inadequate processing results in weak or uneven curls, which can leave the hair looking flat and unstyled.

In contrast, a well-processed perm should give the hair a bouncy and full curl pattern, showcasing volume and movement. Under-processed hair may not hold the intended curl shape, therefore contributing to its limp appearance. The other options do not accurately reflect the typical outcomes of under-processing. For example, maintaining a full curl pattern would indicate a successful perm, while excessive shine and smoothness or no significant change from the natural state would not be linked to hair being under-processed.