This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
Risus-sardonicus term used in: 
Select and explain. 
A. Rabies, B. Tetanus, C. Syphilis, D. Frost-bite
B: Tetanus
Answer: B: Tetanus 
Explanation: (Tetanus): Ref: 840 - H (899-Hn,h)Clinical manifestations of Tetanus* Most common form of the disease is characterized by increased muscle tone and generalized spasms. Median time of onset after injury is 7 days)* Trismus or lockjaw - First noticed increased tone in the masseter muscle* Dysphagia or stiffness or pain in the neck, shoulder and back muscles,* Rigid abdomen and stiff proximal limb muscles, The hand and feet are relatively spared.* Risus sardonicus - Sustained contraction of the facial muscles results in a grimace or sneer* Opisthotonos - Contraction of the back muscles produces on arched back* Cyanosis and threaten ventilation, Deep tendon reflexes may be increased* Other complications include aspiration pneumonia, fractures, muscle rupture, deep vein thrombophlepbitis, pulmonary emboli, decubitus ulcer and rhabdomyolysis