Why Are Hunger and Behaviour in Children So Closely Linked

Why are hunger and behaviour in children so closely linked?

A) Children who fail to eat breakfast typically become hyperactive after eating lunch.
B) The nutrient deficit arising from skipping a breakfast is usually made up over the following 2 days.
C) Children who eat nutritious breakfasts are absent from school less often than their friends who do not.
D) Although breakfast-skippers show reduced attention spans, their scores on intelligence tests remain unaffected.