Perhaps the Most Significant Disadvantage of HPLC Analysis of Hemoglobins

Perhaps the most significant disadvantage of HPLC analysis of hemoglobins is:

A) the technique is only qualitative and not quantitative
B) the technique is associated with a high degree of imprecision
C) the minor differences between the various hemoglobin fractions cause hemoglobins to elute in very narrow, overlapping windows
D) post-translational modification of hemoglobins produces fractions that often elute with the same retention time as other hemoglobin fractions