Which vascular structure is responsible for delivering oxygenated blood to the left atrium?

How would you best describe the role of gene expression in cells a- cells destroy the dna of genes that they do not use b- when cells divide in mitosis, they pass on only the genes that are required. c- to become specialized, cells need to control the production of proteins coded for in their dna d- all genetic information in a cells dna is fully expressed at all times.