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: Biochemistry
Prenatal diagnosis of Hemophilia is best done by: 
Select and explain. 
A. PCR, B. Linkage analysis, C. Cytometry, D. Microarray
A: PCR
Answer: A: PCR 
Explanation: PCR is used in prenatal diagnosis of hemophilia. All direct testing methods are dependent on PCR, so it is the best test for the detection of this disease. Ref: Textbook of Hemophilia By Christine A. Lee, Erik E. Berntorp, W. Keith Hoots, Page 39; Molecular Diagnosis of Genetic Diseases By Rob Elles, Roger Mountford, Page 347; Wintrobe's Atlas of Clinical Hematology By Douglas C. Tkachuk, Jan V. Hirschmann, Page 213.