Scott Suffers from Metabolic Insufficiency X (MIX)disorder

Scott suffers from metabolic insufficiency X (MIX) disorder. His mother also has MIX disorder, but his father does not. What can we conclude?

A) The MIX gene must be recessive.
B) The MIX gene must be dominant.
C) Scott may or may not pass down the gene for MIX disorder to his children.
D) Scott will pass down the MIX disorder to his children, but they may not get the disease.