Which of the following is a signal amplification method?

Branched DNA Amplification (bDNA) is a signal amplification method that allows for the detection of specific nucleic acid sequences with increased sensitivity. This technique utilizes a structure where the initial probe hybridizes to the target nucleic acid, followed by the binding of additional probes, creating a branched structure. Each branch can then further attach to additional labeled probes, effectively amplifying the signal rather than the target DNA itself. This form of signal amplification is particularly useful in situations where the target nucleic acid is present in very low quantities, as it enhances the detection capabilities without requiring multiple rounds of amplification of the target DNA.

In contrast, Polymerase Chain Reaction (PCR) and Real-Time PCR are methods primarily used for targeted amplification of DNA, increasing the amount of the target sequence rather than amplifying the signal directly. While PCR is excellent for amplifying specific DNA sequences, it does not inherently involve the same kind of signal enhancement that bDNA does. Additionally, Restriction Fragment Length Polymorphism (RFLP) is a technique used to analyze the variability in DNA sequences by cutting them with specific restriction enzymes, which does not include a signal amplification aspect. In summary, the key distinction of bDNA as a signal amplification method lies in its