Questions: LO 2.1. What is the main function of white blood cells? To transport oxygen throughout the body. To create and store hormones. To fight infections and foreign invaders. To filter waste from the blood. To regulate body temperature.

The answer is the third one: to fight infections and foreign invaders.

Explanation for each option:

1. To transport oxygen throughout the body: This is incorrect. The main function of red blood cells, not white blood cells, is to transport oxygen throughout the body.
2. To create and store hormones: This is incorrect. Hormone creation and storage are primarily functions of glands in the endocrine system, not white blood cells.
3. To fight infections and foreign invaders: This is correct. White blood cells (leukocytes) are a crucial part of the immune system and are responsible for identifying, attacking, and destroying pathogens such as bacteria, viruses, and other foreign invaders.
4. To filter waste from the blood: This is incorrect. The kidneys are primarily responsible for filtering waste from the blood, not white blood cells.
5. To regulate body temperature: This is incorrect. Body temperature regulation is managed by the hypothalamus and involves various physiological processes, not white blood cells.

Summary: The main function of white blood cells is to fight infections and foreign invaders.