Which of the Following Denotes a Weakness That Is Common

Which of the following denotes a weakness that is common to both the four firm concentration ratio and the HHI?

A) assuming the subject market is poorly defined relative to measuring its concentration of competition
B) case-by-case analysis of the extent of competition is highly subjective.
C) assuming the subject market is well-defined relative to measuring how sales are divided within it.
D) case-by-case analysis of the extent of competition is highly objective.