Question

which sentence from the article would be most important to include in a summary of the article?
a the immune system stores a memory of the germs antigens in a type of white blood cells called b cells.
b this protection against previous illnesses is called immunity.
c for example, doctors suggest a tetanus booster every 10 years to stay immune to the disease.
d tetanus infections continue to decline worldwide.

Explanation:

The main topic is about immunity. Option B defines the concept of immunity which is central to understanding the immune - system related content. Option A is about a specific function of the immune system at the cellular level. Option C is an example of maintaining immunity for a particular disease. Option D is about the trend of a disease. The most important for a summary is the definition of the key concept.

Answer:

B. This protection against previous illnesses is called immunity.