Why are capillaries and not arteries or veins found in alveoli, nephrons, and villi?

Question

1.Vessels must be narrow so that only very small molecules can reach these tissues
2.Vessels must be lightweight so that they do not interfere with the movements of these tissues.

3.Vessel walls must be thin to allow ease of transfer of molecules to these tissues.

4.Vessels must be small so that very little blood enters these tissues.

Answer 1

looks like #3 to me.
The others really make no sense when you think about them.