Which of the following types of gene therapy do you think might be most restricted in the United States today?A. Inserting a normal gene into a liver cell to replace a non-functional gene for a liver protein.B. Inactivating a gene required for HIV infection in precursor cells that give rise to new immune cells in the blood.C. Correcting a mutation that causes hemophilia in the egg cell of a woman, so that none of her children will ever have the disease.D. Clinical trials for a gene therapy of liver disease that involve human subjects.