Which of the following is the portion of a centrifuged urine sample used for microscopic examination?

Artifacts are irregularities or false appearances in microscopic samples that arise during processing rather than being actual components of the urine. They can interfere with the interpretation of the sample but do not represent the biological materials of interest that are found in the sediment.

Casts are cylindrical structures formed in the renal tubules and can be found within the sediment of a urine sample. However, they are a specific type of formed element and not the entire portion of the sample designated for microscopic examination. The sediment encompasses casts along with other particles.

Crystals are solid mineral deposits that can form in urine and may be part of the sediment examined microscopically. Like casts, they represent specific findings rather than the whole section of the sample meant for detailed examination. Sediment includes a wide range of materials, of which crystals are just one type.