Sexually transmitted diseases can be caused by bacteria, viruses, and protozoa. Sexually transmitted diseases caused by protozoa can easily be treated. Bacterial STD can be treated with antibiotics during the initial phase of the disease so bacterial STDs are curable.
Viral STDs are not curable but their symptoms can be managed by taking medication. Viral STDs are not curable because they incorporate their DNA into the host genome and can remain in the latent phase in their host cell.
My best guess would be D. many studies have linked cardiorespiratory exercise to the lowering of blood pressure. (Many studies have also linked going vegan to the lowering of blood pressure, too :)
