Final answer:
The positive result in the VDRL test, used to detect syphilis, is the formation of flocculant, which occurs when anti-treponemal antibodies bind to cardiolipin.
Step-by-step explanation:
The VDRL test, which is used to detect syphilis, relies on the principle that insoluble antigens will form flocculants when bound by antibodies. In the context of this test, anti-treponemal antibodies bind to cardiolipin in suspension. The correct answer to the question is therefore flocculant, as this is the positive result indicating the presence of syphilis. Precipitation reactions involve the formation of a visible antigen-antibody complex known as a precipitin, which occurs when a lattice forms as antibodies bind more and more antigens together.