Final answer:
Bronchoconstriction is the specific cause for narrowing of the lower airways and is typically associated with asthma.
Step-by-step explanation:
The indication of narrowing of the lower airways is most specifically caused by bronchoconstriction. Bronchoconstriction is part of asthma, a chronic inflammatory disease of the lung's airways. During an asthma attack, the airways become inflamed, swollen, and filled with mucus, which leads to narrowing and obstruction of the airways. Asthma is often triggered by environmental factors and can greatly increase the resistance of the respiratory system. In contrast, pneumonia involves the filling of alveoli with fluid, not primarily the narrowing of the airways, and is usually caused by infections. Pulmonary embolism deals with blockage of the pulmonary arteries and pleural effusion involves fluid accumulation in the space around the lungs, neither of which is characterized by airway narrowing due to bronchoconstriction.