The correct answer is C. syphilis.
Syphilis refers to a sexually transmitted infection (STI) where a person is infected by the bacterium, treponema pallidum. In both, males and females, syphilis can infects the genitals, lips, mouth, or anus. Syphilis is diagnosed by blood tests. There are four stages of the STI. In the first stage, painless sores emerge in the area of infection. Whereas, in the second stage, rashes, fever and hair loss can occur.