The correct answer should be gymnastics. While the other mentioned sports could help him too, gymnastics is the most comprehensive one because it involves almost every muscle in the body to do various exercises, whereas biking would increase his leg muscle fitness most, but would not do much for the rest of his body.
The answer in the space provided is anemia. It is because anemia would likely cause other people who has a type of anemia experience a craving of iron or other objects as these are symptoms associated with it. That is why the person who has iron object cravings are needed to be tested if they have some sort of anemia, in order to identify what causes him or her to do it.
Lactose glucose molecules joined together form
