About _________ of the World's Population Resides in the 92

question 49

Multiple Choice

About _________ of the world's population resides in the 92 nations with middle-income economies.

• A) one-half
• B) one-third
• C) one-fourth
• D) one-fifth

---

Definitions:

Venous Valves

Structures within veins that prevent the backward flow of blood, crucial for blood returning to the heart.

Tunica Media

The middle layer of the wall of a blood vessel consisting mainly of smooth muscle cells and elastic fibers, responsible for regulating the diameter of the vessel.

Lumen

The inside space of a tubular structure, such as a blood vessel or intestine.

Carotid Sinus

A dilated area at the base of the internal carotid artery that contains receptors to help regulate blood pressure.