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: Ophthalmology
An 18 year old boy comes to the eye casuality with history of injury with a tennis ball. On examination there is no perforation but there is hyphaema. The most likely source of the blood is - 
Select and explain. 
A. Iris vessels, B. Circulus iridis major, C. Circulus iridis minor, D. Short posterior ciliary vessels
B: Circulus iridis major
Answer: B: Circulus iridis major 
Explanation: When a blunt object strikes the front of the eye, the eye is quickly shortened in antero-posterior direction and, in a compensating fashion, is stretched laterally. This stretching causes breakage of iris vessels, with blood spilling into the anterior and posterior chamber. The most common source of blood is circulus iridis major.