The correct answers are heart disease and cancers. It is no secret that many people in the US are obese - and the more weight they put on, the more likely they are to develop various types of heart diseases, and ultimately have a heart attack. Additionally, the food people eat is usually not of good quality/not healthy, and the lifestyles they are leading are not good for their health, which is why they often develop cancers in the US.
Allan is much more aware of his mortality since his heart attack, and his mom's death, and is learning how diet and diseases are often related. The top two causes of death in the U.S. that are related to dietary factors are heart disease and cancers.
