Answer the following question given this paragraph: 

Unfortunately, maternal mt(DNA)is susceptible to mutations which are a cause of inherited disease, such as breast cancer. Although, it is important to note that most mutations do not lead to defected mtDNA. Heteroplasmy is the presence of a mixture of more than one type of mtDNA. Most people have homoplasmic cells, meaning that their cells contain only normal, undefected mtDNA. However, people with both normal, undefected mtDNA and not normal, defected mtDNA, may inherit mitochondrial diseases. The ultimate condition leading to disease is when the proportion of mutant mtDNA reaches a threshold, after which the cell can no longer cope, resulting in disease. This threshold varies among different tissues and different mutations.


Q: What increases the chances of someone inheriting a mitochondrial disease?

 Choices:

- presence of defect transgenic and defect mtdna

- presence of defect transgenic and undefected mtdna

- presence of defect ornithopods and undefected mtdna

- presence of defect mtdna and undefected mtdna

A:
presence of defect mtdna and undefected mtdna
