Which of the Following Statements Is True About a Population

Which of the following statements is true about a population pyramid?

A) It measures the average equivalent number of years lost due to bad health and disability.
B) It is essential for the understanding of dependency ratios and retirement policy problems.
C) It combines weighted information about morbidity and mortality, and it is expressed in terms of the numbers of healthy years lost.
D) It is a graphical presentation of the health structure of the population.
E) It measures the years lived in good health and is used to calculate healthy adjusted life expectancy.