Which of the following is/are clinical features of tetanus?
The clinical features of tetanus are: 

Trismus combined with pain and stiffness of neck, abdomen and back.
Dysphagia.
Anxious expression (risus sardonicus).
The muscles of neck and trunk become rigid and the back is slightly arched (opisthotonus).
Respiratory failure.
Dysphagia
Risus sardonicus
Opisthotonus
All of the above