A 24 years old male presents to the skin and VD clinic with a painless sore on his genitals that started 1 to 2 weeks back. He gives H / o unprotected sex with a new partner about a month ago. Blood Test confirms the patient has Trepanoma pallidum . Which of the following is the drug of choice for the treatment of this patients infection as a single dose? A Benzathin penicillin.

B Ceftriaxone. C  Aztreonam. D. Vancomycin.