This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
A 34-year-old, G, P0, presents for genetic counselling at 12 week's gestation. The patient has two sisters and a brother; her father
has haemophilia. Her siblings are not affected, but she has a nephew that is: 
Select and explain. 
A. Autosomal recessive, B. X-linked inheritance, C. Mitochondrial inheritance, D. Multifactorial inheritance
B: X-linked inheritance
Answer: B: X-linked inheritance 
Explanation: Haemophilia is an X-linked recessive disease. These diseases are more common in men than in women.
An affected male will not pass the diseases to his sons, but all daughters will be carriers. X-linked recessive diseases are transmitted from carrier women to affected men.