问题：
[单选题]What can we infer from the sentence “The link between diet and well-being is something we learn early in life — and then forget over and over again until we die.” (Para. 5)
ADiet-related diseases usually come with unhealthy eating habit.
BWe learnt how to keep healthy when we were young.
CIt is important to keep a healthy diet.
DWe are always aware that diet keeps us fit, but it is very hard for us to do it.
