In the Introduction to This Chapter, the Use of the CRISPR-Cas9

In the introduction to this chapter, the use of the CRISPR-Cas9 system to make a deletion of exon 23 containing a premature stop codon in mdx mice was described. The resulting mice had partially restored dystrophin protein and muscle function. Which of the following CRISRP-Cas9 mediated changes might lead to a better restoration of dystrophin protein and muscle function?

A) A deletion of exon 24 in addition to exon 23
B) A deletion of intron 23
C) A deletion of 30 bases within exon 23
D) A deletion of 25 bases within exon 21
E) An insertion of a corrected copy of exon 23 after the mutant exon 23