What type of control monitors specific steps of an amplification method?

The correct answer is internal control. Internal controls play a critical role in ensuring the reliability of amplification methods, such as polymerase chain reaction (PCR). They are incorporated into the assay to monitor the entire process from sample extraction through amplification, helping to verify that every step of the procedure is functioning correctly.

An internal control typically consists of a target sequence that is co-amplified with the specific target of interest. This allows the laboratory to confirm that the amplification process is effective and that the reagents and conditions are suitable. If the internal control fails to amplify, it indicates a potential issue with the sample preparation or the amplification process itself, prompting a re-evaluation of the procedure.

While other types of controls exist, such as positive controls which help confirm that the assay can detect the target under optimal conditions, and external controls which may provide information about the performance of the method across different runs, they do not specifically monitor the internal steps of the amplification method like internal controls do. Therefore, the emphasis on monitoring specific steps of the amplification process distinctly aligns with the function of internal controls.