<prompt> The preferred treatment option for primary syphilis is -Injection benzathine pencillin 2.4 million units IM single doseInjection benzathine pencillin 2.4 million units IM once a week for 3 weeksCap. doxycycline 100 mg orally twice a day for 2 weeksTab. azithromycin 2 gm single dose  <response>: Ans. is a i.e.,Injection benzathine pencillin 2.4 million units IM single dose 