Which of the following is a primary component of a dialyzer?

A semipermeable membrane is a primary component of a dialyzer because it plays a critical role in the dialysis process. The dialyzer, often referred to as an artificial kidney, uses the semipermeable membrane to facilitate the removal of waste products and excess fluids from the blood. This membrane allows certain small molecules, such as urea and creatinine, to pass through while retaining larger molecules, such as proteins and blood cells. The selective permeability of the membrane is essential for effectively cleansing the blood during hemodialysis.

The other options, while related to the dialysis process, do not serve as the primary structural or functional component of the dialyzer itself. An artificial organ is a broader term that could encompass the whole dialysis system, but it does not specifically denote the key functional element. A blood pump is a device used to move blood through the dialyzer but is not a component of the dialyzer itself. Similarly, a biological filter generally describes a different function in biological systems and is not specific to the technology of dialysis.