A Previously Healthy Man Is Diagnosed with Both Secondary Syphilis

A previously healthy man is diagnosed with both secondary syphilis and HIV. What is the most likely way he contracted HIV?

A) He had unprotected sex with one partner who had contracted syphilis 18 months before their encounter and was also HIV positive; HIV and syphilis are usually transferred together.
B) He had unprotected sex with an HIV positive partner while he had open chancres from primary syphilis, which increased his risk for contracting HIV.
C) He had protected sex with an HIV positive partner while his syphilis was in its second year of latency.
D) He must have recently had unprotected sex with two differently infected partners; HIV and syphilis must be transferred independently, from different sexual partners.
E) The syphilis spirochete attacked his immune system, making it easier for him to contract HIV from nonsexual contact.