What disease affects the nervous system and can cause numbness or abnormal sensations?

The correct answer is Neuropathy, as it specifically refers to a condition that affects the nerves and can lead to symptoms such as numbness, tingling, or abnormal sensations. Neuropathy often results from damage to the peripheral nerves and can be caused by various factors, including diabetes, infections, injuries, and certain medications. The hallmark symptoms arise from the type of nerve that is affected, which can disrupt the normal communication between the nerves and the brain, leading to the abnormal sensations that are characteristic of this condition.

In contrast, muscle strain, arthritis, and tendonitis primarily involve the musculoskeletal system rather than directly affecting the nervous system. Muscle strain is related to the overstretching or tearing of muscles, arthritis is an inflammation of the joints affecting mobility and comfort, while tendonitis involves inflammation of the tendons typically due to overuse. None of these conditions are primarily associated with numbness or abnormal sensations in the way that neuropathy is.