A 42-year-old man comes to the Emergency Department with persistent pain, especially during exercise, of his right lower leg over the past 2-months. The pain first started when he distorted the right lower leg while climbing up the stairs; he noticed a torrential sound and suffered from immediate pain with immobilisation. Clinical investigation reveals pain in the right medial calf when the knee is placed in maximal extension and the ankle is passively dorsiflexed. Which of the following structures is injured and causing his pain?
A. Anterior cruciate ligament
B. Gastrocnemius muscle
C. Patellar ligament
D. Popliteus muscle
E. Posterior cruciate ligament
F. Soleus muscle