Typically,the Weakest of the Five Competitive Forces in an Industry

Typically,the weakest of the five competitive forces in an industry is/are:

A) the threat posed by potential new entrants.
B) the bargaining power and leverage that suppliers are able to exercise.
C) the competitive pressures that stem from the ready availability of attractively priced substitute products.
D) the bargaining power and leverage that buyers are able to exercise.
E) None of these is typically the weakest.