What are the three main types of specimens collected in a laboratory?

The correct choice identifies blood, urine, and tissue as the three main types of specimens collected in a laboratory, and this selection reflects commonly utilized biological specimens in clinical testing.

Blood specimens are crucial for a wide range of tests, including hematology, chemistry, and immunology, helping diagnose and monitor various health conditions. Urine specimens are fundamental for urinalysis and can provide insights into metabolic and kidney function, as well as screen for drugs and other substances. Tissue specimens, which can be obtained via biopsies, are essential for histopathological examinations and cancer diagnostics, as they allow for the assessment of cellular structures and potential disease processes.

The other options include combinations of specimens that are not as standard or widespread. While saliva and sputum can be useful in specific testing scenarios, they do not match the broad clinical application of blood and urine. Hair and skin may offer some diagnostic value but are not routinely used as primary specimen types for laboratory testing compared to blood, urine, or tissue.