The presence of foreign antigens cause the immune system to produce antibodies.
True
False

True.

Explanation:

This is how you fight infections, as well as the reason people have allergies. Anything foreign in places it shouldn't be (e.g. the blood stream) is considered a threat to the body. Some people have a stronger response than others.

the more fit you are, the faster the recovery. your heart rate drops most sharply in the first minute after you stop exercising; it should then fall about 20 beats a minute—a drop of less than 12 beats a minute is considered abnormal. this “recovery heart rate” is measured as part of an exercise stress test.