<s>[INST] context: UV light 3) Microscopic examination - Involves identification of spermatozoa under the microscope. Fluorescence microscopy is based on the principle that the Y-chromosome is fluorescent to quinacrine. 4) Electrophoretic methods Acid phosphatase isoenzyme test - Polyacrylamide gel electrophoresis followed by staining with methyl umbelliferyl phosphate reagent makes the seminal acid phosphatase to be distinguished from the acid phosphatase present in other substances & in vaginal secretion. This is superior to LDH isoenzyme method since semen can be identified in the absence of sperms as in azoospermic or vasectomised persons. Lactate dehydrogenase (LDH) isoenzyme Test - Sperm specific LDH isoenzyme can be separated from other LDH isoenzymes of semen by polyacrylamide gel electrophoresis. Proof of semen: The only absolute proof of semen is the finding of at least one unbroken spermatozoan, or electrophoretic LHD isoenzyme detection of sperms. In case of azoospermia, vasectomy or very old persons a stain will be seminal if it gives - characteristic fluorescence in UV light - positive 1-taarate acid-phosphatase and - High levels of acid phosphatase & creatine phosphokinase or electrophoretic seminal acid phosphatase or PSA (P30) positive Species (Human or animal) is confirmed by precipitin test as in blood stains. Source (from which person) is identified by DNA & different grouping systems such as ABO, GM, PGM & GLO-I. New test Commercial ELISA, the SEMA(r)assay, for a seminal vesicle-specific antigen (SVSA) provides highly sensitive detection of semen but are costly . [/INST] question: Dried semen stain in clothes is identified by | options: A: UV light B: Spectroscopy C: Magnifying lens D: Infra red | answer: A </s>