Layers of Blood Vessels

Q.

Which leg has the main artery?

Q. Assertion: The arteries are not collapsible when they are empty.
Reason: Arteries are situated deeply in the body.

1. Both the assertion and reason are true and the reason is the correct explanation for the assertion
2. Both the assertion and reason are true but the reason is not the correct explanation for the assertion
3. Assertion is true but the reason is false
4. Reason is true but the assertion is false

Q. pace maker is the bundle of

Q. Why oxygen does diffuses into the blood capillaries in the lungs, but out of the blood capillaries in the tissues.