The nociception caused by the severe pain and drives to CNS for information processing. The chronic pain causes pshychological distress.
This distress is going to be caused by the abnormal psychological feelings are mainly due to abnormal alterations in neurotransmitter levels in central nervous system. This psychological distress would further cause pain much worse than normal.
Thus, the options (b), (c) and (a) are incorrect.
This distress is going to be caused by the abnormal psychological feelings are mainly due to abnormal alterations in neurotransmitter levels in central nervous system.
Therefore, the correct option is – d). Pain may cause psychological distress, and psychological distress may make the experience of pain worse.