Correct the following statements by changing the first/ last word only :

1. BCG is a kind of vaccine used to prevent Pneumonia.
2. Streptomycin is a kind of vaccine.
3. Breathing is a bio-chemical process.
4. The amount of oxygen in expired air is 21%.
5. The front opening of the trachea is guarded by a muscular flap called diaphragm.

The basic structural and functional unit of the lungs is :

1. Pleura
2. Alveolus
3. Capillary
4. Diaphragm

The diagram given alongside shows the "Human Respiratory System". Study the same and answer the following questions :

(i) Label the guidelines 1 to 4.

(ii) Define the structure shown as part 2.

(iii) Name the basic structural and functional unit of part 3.

(iv) Write one specific structural feature of the inner lining of part 1.

(v) What is the muscular sheet on which part 3 rests ?

Assertion (A): The main pulmonary artery pumps oxygenated blood from the right ventricle into the lungs.

Reason (R): Inside the lungs, the artery divides and divides several times to form capillaries around the air sacs.

1. A is True, and R is false.
2. A is False, and R is true.
3. Both A and R are true.
4. Both A and R are false.