You will hear a recording. Select the paragraph that best relates to the recording.

1. The way that immune system works is remarkably complex. Skin, the first line of defense, can keep foreign objects out of the body, while the white blood cells, acting like soldiers fighting invaders, can fight pathogens in the body.

2. There are two major types of immune that organisms have: innate and adaptive. The skin and mucus are part of adaptive immune system.

3. The skin, the body’s first line of defense, helps animals fight off diseases. Also, the mucus in nose prevents airborne foreign bodies—many of which do very little good—from entering the body.

4. White blood cells are responsible for fighting the pathogens inside the body. Pathogens can enter bodies and cause them to become sick. However, the white blood cells are not always effective.

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