Estimating the relative cost of human lives (i.e., DALYs) has been critiqued as ethically and methodologically ambiguous. What is the main criticism of estimating the cost of human lives?
1) It is difficult to assign a monetary value to human life
2) It is not necessary to estimate the cost of human lives
3) Estimating the cost of human lives is a straightforward process
4) There is no ethical or methodological ambiguity in estimating the cost of human lives