What is the primary function of arterial blood gas (ABG) tests?

The primary function of arterial blood gas (ABG) tests is to measure levels of oxygen and carbon dioxide in the blood. This information is essential for assessing a patient's respiratory status and determining how well gases are being exchanged in the lungs. ABG tests provide critical insights into the effectiveness of ventilation, as well as the acid-base balance in the body, which can be indicative of various physiological conditions such as respiratory failure, metabolic disorders, or complications from other health issues.

Assessing blood cholesterol levels, evaluating liver function, and testing for infections pertain to different types of diagnostic tests and are not the focus of ABG assessments. Therefore, option B is the correct answer as it accurately summarizes the purpose and significance of ABG testing in clinical settings.