OK, so if I remember correctly this is the one that shows the inheritance pattern. mitochondrial is also passed by the mother; however, it can have variable expressivity and incomplete penetrance, which is why some members were not affected.
Got this one wrong because of those 2 unaffected children. Here's the explanation from FA pg 59:
Mitochondrial inheritance - Transmitted only through the mother. All offspring of affected females may show signs of disease.
Variable expression in a population or even within a family due to heteroplasmy.
Heteroplasmy basically means that multiple mitochondria are transmitted to each offspring. Their ratio may change at each generation, and cause more severe or less severe disease, even within the same family.
Those unaffected dudes lucked out.