The 'symptomless' period or latent period in case of syphilis may last for

Syphilis is an infectious bacterial disease caused by $Treponema\ pallidum$ with $3$ stages:
$(A)$ Infectious painless ulcers on the genitals $\quad(i)$ First
$(B)$ Blindness, heart trouble, aortic impairment $\quad(ii)$ Second
$(C)$ Skin lesions, hair loss, swollen joints $\quad(iii)$ Third
Which of the following is the correct match between the symptoms and stage?

Which of the following principles are used to prevent $STD$ infection?
$(i)$ Avoid sex with unknown partners
$(ii)$ Use condoms during coitus
$(iii)$ Blood transfusion
$(iv)$ All of these

Which of the following is an important detection technique for syphilis?

Which of the following is not a sexually transmitted disease?

Which of the following sexually transmitted diseases is not completely curable?