5) B

Let us first name the areas first.

Area 1 is the brain
Area 2 is the bronchi
Area 3 is alveoli
Area 4 is the blood vessel

We know bronchitis will occur in the bronchi. Therefore area 2 will be affected by bronchitis. We can eliminate option C, D, E and F.

We know that nicotine which is present in cigarettes affects the brain which is area 1. Therefore, we can eliminate option A.

Carbon monoxide affects the red blood cells in blood which travels in the blood vessels (area 4). Carbon monoxide inhibits the uptake of oxygen in haemoglobin.

Emphysema is a disease which damages the alveoli, so emphysema would affect the alveoli (area 3).

Hence, the correct answer is option B.