This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Medicine
A 9-year-old boy presents to the clinic for evaluation of easy bruising. Investigations confirm the diagnosis of hemophilia A. Which of the following is the most common presentation of hemophilia A? 
Select and explain. 
A. hematuria, B. melena, C. hemarthrosis, D. pressure neuropathy
C: hemarthrosis
Answer: C: hemarthrosis 
Explanation: The most common presentation is hemarthrosis with pain in a weight-bearing joint such as the hip, knee, or ankle. Hematuria is also common. Bleeding can occur at almost any site without prior trauma.