Oxygen moves from the lungs to the blood a. by way of simple diffusion because the oxygen concentration in the blood is lower than than the lungs and diffuses down its concentration gradient.
b. by way of active transport requiring energy to overcome the repulsive forces of the cell membrane.
c. by way of facilitated diffusion through a protein channel in the cell membrane since oxygen would normally be repelled by the membrane.
d. by way of active transport to build up the oxygen concentration in the blood.