Which of the following techniques is NOT considered a form of signal amplification?

Quorum sensing is a process used by bacteria to communicate and coordinate their behavior through the release and detection of signaling molecules. This process allows bacterial populations to act collectively in a coordinated manner, such as in biofilm formation or virulence factor production. However, it does not involve any method of amplifying signals at the molecular or genetic level, which is typically characterized by techniques directed toward enhancing the detection sensitivity of specific nucleic acid sequences.

In scientific contexts, signal amplification techniques aim to increase the detectability of low-abundance analytes, often involving nucleic acid-based methodologies. Techniques like Hybrid Capture, Cycling Probe, and Transcription-based amplification utilize biological processes to multiply signals such that even minuscule amounts of target nucleic acids can be identified, making them valuable in various diagnostic applications.

Thus, within this question, quorum sensing stands out as a biological communication mechanism rather than an amplification technique, making it the correct choice for the question.