<prompt> 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 -Tendon strengthBone strengthMuscle strengthMusculotendinous junction strength  <response>: 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. 