Explanation:
The correct option is 'd'. The Thompson test (or Simmonds-Thompson test) is the most reliable clinical test for an Achilles tendon rupture. With the patient prone and the foot hanging off the table, the examiner squeezes the calf muscle belly. Normally, this elicits passive plantarflexion of the ankle. If the Achilles tendon is completely ruptured, squeezing the calf will not result in plantarflexion (a positive test).

Reference: Thompson TC. A test for rupture of the tendo achillis. Acta Orthop Scand. 1962;32:461-465.