Which one of the following techniques does not serve the purpose of early diagnosis of a disease for its early treatment? 

Serum and urine analysis can indeed have limitations in achieving early detection.
Serum analysis involves examining blood samples to measure the levels of various components, such as proteins, hormones, enzymes and metabolites. However, serum analysis alone may not always be sufficlient for early detection as some diseases might not manifest significant changes in blood components in the early stages.
Similarly, urine analysis involves evaluating urine samples to detect abnormalities, such as the presence of certain substances, cells or metabolites. Urine analysis also has limitations in early diagnosis sinced some diseases may not result in detectable changes in urine composition during the initial stages.
To overcome these limitations, advanced techniques like recombinant DNA technology, PCR, and ELISA have been
Developed and are used in early diagnosis. These techniques allow for the detection of specific molecules, genetic material, or antibodies associated with diseases even before the disease starts producing its signs and symptoms.
(1) ELISA can detect specific antibodies or antigens associated with autoimmune disorders or certain infections. For
Example, it is widely used as a screening test or HIV infection.
(2) Recombinant DNA technology has enabled the development of diagnostic tests for genetic diseases, where
Specific genetic mutations or markers can be identified at an early stage.
(4) Polymerase chain reaction (PCR) helps in early diagnosis of diseases. It allows for the amplification of specific
DNA sequences, making it possible to detect and analyze even tiny amounts of genetic material of infectious agents
Present in a sample.