Final answer:
The 4th stage of syphilis is known as tertiary syphilis, which can cause severe organ damage and may be fatal if not treated.
Step-by-step explanation:
The 4th stage of syphilis is D. Tertiary syphilis. This is the final and most severe phase of the infection that can occur 10 to 20 years after initial infection. Tertiary syphilis can lead to severe health problems including damage to internal organs like the brain, heart, liver, or bones.
It can also cause serious conditions such as paralysis, blindness, seizures, and dementia, and in some cases, it can be fatal.
The 4th stage of syphilis is Tertiary syphilis. In this stage, the disease can infect and damage internal organs, such as the brain, heart, liver, or bones. Symptoms of tertiary syphilis may include paralysis, blindness, seizures, and dementia, and the damage can be serious enough to cause death.
Therefore answer is D. Tertiary syphilis.