"a tissue section is fixed to a microscope slide, then incubated with a fluorescently labeled antibody that binds to an antigen expressed by cells in that tissue. the preparation is then washed and inspected with a fluorescent microscope. this technique is called: "

The question is incomplete as it does not have the options which are:

A. direct immunofluorescence.

B. indirect immunofluorescence.

C. fluorescence polarization.

D. autofluorescence.

The correct answer will be option-A

Explanation:

Direct immunofluorescence or the primary fluorescence is a technique used in the laboratories to diagnose the disease related to kidney, skin and other organ systems.

The technique is performed by applying antibody–fluorophore conjugate molecules to the antigen expressed by the cells of the infected tissue.

When the tissue is observed with a fluorescent microscope, the fluorophore emits light of its own wavelength which help analyse the antigen and the staining pattern in the tissue.

Thus, option-A is the correct answer.