Can a mutation be beneficial to an organism?

a. no, because any change to existing dna is harmful.
b. no, because mutations are caused by exposure to harmful radiation.
c. yes, because a mutation can an organism survive in a particular environment.
d. yes, because a mutation can give an organism what it needs to survive.

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.