Based Upon the Discussion of Infant Mortality in the Text

Based upon the discussion of infant mortality in the text, which conclusion appears to be implied and/or stated:

A) While the disparities in overall life expectancy between the U.S. and countries that spend a greater percentage of GDP on health care do not, alone, demonstrate that the U.S. health system functions only moderately well or poorly, the argument becomes irrefutable when combined with the fact that the U.S. does not have the lowest infant mortality rate
B) Other factors may differentially contribute to the U.S.'s higher than expected infant mortality rates such as: 1) differential rates of multiple births; 2) differential demographic and socio-economic variables such as maternal age, marital status, education, etc.; 3) differential health conditions in the mothers who gave birth
C) None of the above are true
D) Both a and b are strong arguments