Which of the following statements about asthma is true?

The statement regarding asthma being triggered by environmental factors is true because asthma is a chronic respiratory condition characterized by inflammation and narrowing of the airways, which can be significantly influenced by various environmental triggers. Common triggers include allergens such as pollen, mold, pet dander, and dust mites, as well as irritants like smoke, air pollution, and strong odors. In addition, weather changes and physical activity can also contribute to asthma exacerbations.

The other statements do not accurately reflect the nature and complexities of asthma. It is not solely a childhood disease, as asthma can develop at any age. While medication plays a critical role in managing asthma, not all cases can be fully controlled due to variability in individual responses to treatment and the influence of persistent environmental factors. Lastly, asthma primarily affects the lungs, but the condition can also have systemic effects and exacerbate comorbidities, indicating that it is not limited to the respiratory system alone.