Which of the following makes asthma a serious health problem in America?​

A) ​Its mortality rate is high, and also rising.
B) ​It is the biggest cause of child disability.
C) ​It causes the most school absence days.
D) ​Both (b) and (c) do, but (a) is incorrect.

While asthma mortality rates have decreased over the years, it still accounts for a significant number of deaths in the United States. However, the biggest impact of asthma is on children who experience disability due to the condition and miss school days, affecting their education and overall well-being. Therefore, both options (b) and (c) are correct, but (a) is incorrect as the mortality rate, while a concern, is not the primary reason why asthma is a serious health problem in America.