Critics of Ehrlich's Death Penalty Research Assert That His Formula

Critics of Ehrlich's death penalty research assert that his formula

A) does not control of the variables that affect the murder rate
B) explains trends between the 1930s and 1960s but does not explain trends between the 1980s and 1990s
C) does not explain trends between the 1930s and 1960s when executions declined while the crime rate declined or remained stable
D) cannot explain trends during the moratorium on the death penalty from 1972-1976