Answer :
D is the correct answer. - A dense network of capillaries surrounds them.
Capillaries are very small about 1 cell thick which makes them more suitable to exchanging gases rather than a vein or an artery.Capillaries allow the exchange of gases, nutrients and fluids by the process of diffusion between the body and the body tissues.
Capillaries are very small about 1 cell thick which makes them more suitable to exchanging gases rather than a vein or an artery.Capillaries allow the exchange of gases, nutrients and fluids by the process of diffusion between the body and the body tissues.