A good vector to genetically altered respiratory cells might be A VIRUS THAT HAS BEEN GENETICALLY ALTERED TO CARRY NORMAL HUMAN DNA.
Gene therapy is a medical method of treatment which uses genes to prevent or treat diseases. The method is used to correct the defects in genes which is causing a disease. In order to insert a normal gene to replace the defective one, a vector, which will carry the gene is needed. The vector that is usually used in this case is a virus, which has been doctored to carry a normal human DNA.
Option B. A man pushes a couch across the room is the answer.
It seems to have choices. The exposure mutagens may lead to the mutation. When the mutation add up to a certain amount and can lead to cancer. So exposure mutagens will increase the cancer risk.
