Which of the following is a common symptom of Parkinson's disease?

Tremors are indeed a common and hallmark symptom of Parkinson's disease. They typically manifest as rhythmic shaking that often begins in the hands, though they can also affect other parts of the body. This characteristic tremor is known as a "resting tremor," meaning it is usually most noticeable when the individual is at rest and may decrease or disappear with voluntary movement. The presence of tremors is one of the key diagnostic criteria for Parkinson's, alongside other symptoms such as bradykinesia (slowness of movement), stiffness, and postural instability.

In the context of Parkinson's disease, while loss of coordination, severe headaches, and lifestyle changes can be relevant to neurological disorders or may occur in patients, they do not specifically identify the disease in the same way that tremors do. Loss of coordination may be associated with other conditions and isn't a primary symptom of Parkinson's. Severe headaches are not commonly linked to Parkinson's but could involve other issues. Lifestyle changes can occur as a result of living with the disease, but they are not direct symptoms of Parkinson's itself. Hence, tremors stand out as a definitive and typical manifestation of Parkinson's disease.