Name the most likely mode of inheritance in the following pedigree: <image 1>
['autosomal recessive (AR)', 'autosomal dominant (AD)', 'X-linked recessive (XR)', 'X-linked dominant (XD)']
The mode of inheritance is most likely AD, since every affected individual has an affected parent, and the disease is inherited even in four different matings to unrelated, unaffected individuals. It is very unlikely that it is XD or XR, in part because affected father had an affected son.