After Reading the Paragraph Below, Answer the Question That Follows

After reading the paragraph below, answer the question that follows.
Gene therapy is a relatively new approach to treating inherited disorders. In effect, a good, working copy of the affected gene is introduced into multiple cells on an expression vector (typically a virus) . The good gene is incorporated into the genome of each cell, thus providing the information missing due to the host cell's mutated gene.
-Which of the following statements regarding gene therapy is incorrect?

A) Successful infection of the good gene into tissue resident stem cells will promote the gradual replacement of 'bad' cells with 'good' ones, i.e. those that have a good copy of the gene.
B) Successful infection of the good gene into post-mitotic tissue cells will require that a great many individual cells take up and incorporate the good gene.
C) Once the good gene is incorporated into a cell's genome, there is effectively no mechanism to remove it.
D) A 'bad' gene product can still overcome the benefit of the 'good' gene and this is called a dominant negative effect.