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: Orthopaedics
There is spontaneous rupture of the Achilles tendon in an 18-year-old male. It is most likely to be due to excess stress beyond - 
Select and explain. 
A. Tendon strength, B. Bone strength, C. Muscle strength, D. Musculotendinous junction strength
A: Tendon strength
Answer: A: Tendon strength 
Explanation: A rupture of the Achilles tendon occurs when the tendon is stretched outside beyond its capacity.
The most common site of rupture is the "watershed" less vascular area of tendon, which is 4 cm proximal to its insertion on calcaneum.