Just need help explaining this, I look it up and it no use

O+ x AB- = -A(O)

Explanation: Remember that Rh- is recessive the father may have recessive RH-

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.

i think it is dna, i'm not totally sure but i think it might be.