Pedigree Analysis: Problem
The key here is that it is a question about mitochondrial DNA. mtDNA in humans is inherited maternally (from the mother). Both sons and daughters inherit mtDNA, but only the daughters will pass it on to the next generation.

A child's mtDNA has to come from his or her mother, and all of a person's mitochondria are genetically identical. Therefore, children of an affected female will almost certainly have the abnormal trait, while children of an affected male will not.