Question

When and how does the RT-PCR test detect the presence of the virus? During PCR. by adding a fluorescent dye and a quencher dye which will be degraded if DNA polymerase finds the viral gene. The sample if positive fluoresces. After PCR, by adding a fluorescent dye which will be activated once the sample goes through a special laser. During PCR, by adding fluorescent primers that are detected through a special laser. After PCR, by adding a quencher dye which is activated when the viral DNA is available in high concentrations

Answer 1

Reverse transcription polymerase chain reaction (RT-PCR) is a laboratory technique combining reverse transcription of RNA into DNA (in this context called complementary DNA or cDNA) and amplification of specific DNA targets using polymerase chain reaction (PCR).
During RT-PCR, fluorescent dye is added during the PCR, but not after the PCR.

Hence, first option is the correct answer.