What is an incorrect match between method and its objective?

The combination of Knott's concentration and the recovery of operculated helminth eggs does not align with the primary objective of the Knott's concentration technique. This method is specifically designed to concentrate and examine filarial parasites, such as microfilariae in blood samples, rather than focusing on the recovery of operculated helminth eggs, which are typically assessed using different concentration techniques.

The Knott's concentration technique is valuable in situations where the presence of filarial infections needs to be confirmed, making it essential for diagnosing lymphatic filariasis or other diseases caused by filarial nematodes. Operculated helminth eggs, such as those from schistosomes, require alternative methods like sedimentation or flotation techniques that are more suited for the identification and recovery of such helminths from fecal samples.

In contrast to this, direct wet examination is effectively used for detecting organism motility, Baermann's technique is specifically aimed at recovering larvae, particularly for Strongyloides, and a permanent stained fecal smear provides a reliable method for confirming the presence of protozoa in stool samples.