An example of an upper respiratory infection is:

A. Hypoxemia specifically refers to low levels of oxygen in the arterial blood, which can lead to tissue hypoxia if not corrected. It is often detected through arterial blood gas (ABG) analysis or pulse oximetry.
B. Excess oxygen in the blood is rare and may occur with supplemental oxygen therapy, but it is not the definition of hypoxemia.
C. Excess oxygen in the tissues is not a standard clinical term and does not relate to the condition known as hypoxemia.
D. Excess carbon dioxide in the blood is called hypercapnia, not hypoxemia.

A. Crackles are discontinuous, short popping sounds that are often heard during inhalation and are typically associated with conditions like pneumonia or pulmonary edema, not asthma.
B. Wheezes are continuous, high-pitched sounds often heard during exhalation and are commonly associated with asthma or other obstructive airway conditions. These sounds are caused by the narrowing of the airways.
C. Stridor is a harsh, high-pitched sound often heard during inhalation and indicates upper airway obstruction, such as in croup or a foreign body in the airway.
D. Rhonchi are low-pitched, gurgling sounds that are often associated with blockages in the larger airways (such as mucus) and are generally heard during both inhalation and exhalation, but they are not typically high-pitched like wheezes.