Cigarette smoking leads to emphysema. In this disease, terminal bronchioles get obstructed and reduce the ventilation of the alveoli connected to them. Many alveoli coalesce together to form large chambers due to destruction of their walls. This change of smaller alveoli to large chambers reducing the area of alveolar surface across which gases are exchanged. All these changes reduce both oxygen uptake and carbon dioxide elimination.

Emphysema is a chronic lung disease characterized by the destruction of the walls of the alveoli, resulting in the reduction of the surface area available for gas exchange. The correct match for this condition is option 'A'.

Emphysema: Reduction of surface area of alveoli and bronchi

Explanation:

1. Emphysema:
- Emphysema is a type of chronic obstructive pulmonary disease (COPD) that primarily affects the alveoli, which are tiny air sacs in the lungs responsible for the exchange of oxygen and carbon dioxide.
- In emphysema, prolonged exposure to irritants such as cigarette smoke or air pollution leads to the destruction of the walls of the alveoli.
- This destruction causes the alveoli to lose their elasticity and ability to recoil, leading to the permanent enlargement of air spaces and reduction of the surface area available for gas exchange.
- As a result, the individual may experience symptoms such as shortness of breath, coughing, and wheezing.

2. Pneumonia:
- Pneumonia is an infection that primarily affects the lung tissue.
- It is usually caused by bacteria, viruses, or fungi and can lead to inflammation and fluid accumulation in the alveoli.
- Occupational diseases, on the other hand, are conditions that are caused by exposure to certain substances or conditions in the workplace.
- Pneumonia is not typically considered an occupational disease caused by asbestos exposure.

3. Silicosis:
- Silicosis is a lung disease caused by the inhalation of crystalline silica dust, usually in occupational settings such as mining, construction, or sandblasting.
- In silicosis, the inhaled silica particles cause inflammation and scarring in the lungs.
- This scarring can lead to the formation of nodules and fibrosis, impairing the normal functioning of the lungs.
- Silicosis primarily affects the upper lobes of the lungs and is characterized by symptoms such as cough, shortness of breath, and chest pain.

4. Asthma:
- Asthma is a chronic inflammatory disease of the airways.
- It is characterized by recurrent episodes of wheezing, breathlessness, chest tightness, and coughing.
- In asthma, the airways become inflamed and narrowed in response to certain triggers, such as allergens, irritants, or exercise.
- Excessive secretion of bronchial mucus is not a defining characteristic of asthma, although increased mucus production can occur during asthma attacks.

Therefore, the correct match is:

Emphysema: Reduction of surface area of alveoli and bronchi (option 'A').